Visualization of network health information

ABSTRACT

A determination is made that a graphical representation of network health state information pertaining to a client account of a provider network is to be provided. Using respective network metrics groups corresponding to several data sources, a network health state descriptor corresponding to a resource associated with the client account is generated. A data set usable to generate a graphical display of network health state information of the resource of the client account is transmitted.

BACKGROUND

Many companies and other organizations operate computer networks thatinterconnect numerous computing systems to support their operations,such as with the computing systems being co-located (e.g., as part of alocal network) or instead located in multiple distinct geographicallocations (e.g., connected via one or more private or publicintermediate networks). For example, data centers housing significantnumbers of interconnected computing systems have become commonplace,such as private data centers that are operated by and on behalf of asingle organization, and public data centers that are operated byentities as businesses to provide computing resources to customers. Somepublic data center operators provide network access, power, and secureinstallation facilities for hardware owned by various customers, whileother public data center operators provide “full service” facilitiesthat also include hardware resources made available for use by theircustomers.

The advent of virtualization technologies for commodity hardware hasprovided benefits with respect to managing large-scale computingresources for many customers with diverse needs, allowing variouscomputing resources to be efficiently and securely shared by multiplecustomers. For example, virtualization technologies may allow a singlephysical virtualization host to be shared among multiple users byproviding each user with one or more virtual machines hosted by thesingle virtualization host. Each such virtual machine may represent asoftware simulation acting as a distinct logical computing system thatprovides users with the illusion that they are the sole operators of agiven hardware computing resource, while also providing applicationisolation and security among the various virtual machines. Furthermore,some virtualization technologies are capable of providing virtualresources that span two or more physical resources, such as a singlevirtual machine with multiple virtual processors that spans multipledistinct physical computing systems.

In many cases, customers of virtualized computing services may not havemuch control over the specific virtualization hosts selected for theirvirtual machines, or over the network paths that may be used for inboundand outbound traffic of their virtual machines. Instead, customers mayrely on the provider of the virtualized computing service to selectvirtualization hosts and network paths that are capable of supportingthe desired levels of performance, availability, and the like. From thecustomers' perspectives, various types of resources allocated for theiruse may sometimes appear to be “black boxes”, with few tools availablefor detailed troubleshooting or analysis. As a result, when applicationsappear to be experiencing performance or functional problems, it may notbe straightforward for the customers to quickly determine whether theproblems result from infrastructure issues which are out of thecustomers' direct control, or whether the problems are caused byapplication bugs or customer-generated configuration errors.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example system environment in which metrics from avariety of data sources may be aggregated to provide network healthstate information to customers of one or more provider network servicesvia programmatic interfaces, according to at least some embodiments.

FIG. 2 illustrates an example scenario in which output produced by avariety of intermediary tools may be used to generate network healthstate information, according to at least some embodiments.

FIG. 3 illustrates example components of a network health managementservice node, according to at least some embodiments.

FIG. 4 illustrates example elements of a network health state descriptorwhich may be used to store information aggregated on behalf of acustomer, according to at least some embodiments.

FIG. 5 illustrates example elements of a network health state requestwhich may be transmitted via a programmatic interface supported by anetwork health management service, according to at least someembodiments.

FIG. 6 illustrates example data sources from which networking-relatedmetrics pertaining to guest virtual machines of a virtualized computingservice may be obtained, according to at least some embodiments.

FIG. 7 illustrates an example hierarchy of resources of a virtualizedcomputing service, according to at least some embodiments.

FIG. 8 illustrates examples of isolated virtual networks which may beestablished on behalf of customers of a virtualized computing service,according to at least some embodiments.

FIG. 9 illustrates examples of endpoint pair categories for whichrespective health state information reports may be provided to clientsof a network health management service, according to at least someembodiments.

FIG. 10 illustrates an example web-based interface which may be used toprovide high-level network health state information to a client of avirtualized computing service, according to at least some embodiments.

FIG. 11 illustrates an example web-based interface which may be used toprovide network health state information at the level of individualvirtual machines to a client of a virtualized computing service,according to at least some embodiments.

FIG. 12 illustrates an example web-based interface which may be used tospecify health-related metrics to be displayed with respect to variousresources allocated to a client, according to at least some embodiments.

FIG. 13 illustrates examples of tools from which data may be collectedat a network health management service, according to at least someembodiments.

FIG. 14 illustrates examples of guest virtual machines which may beestablished as part of a connectivity verifier tool whose output is usedby a network health management service, according to at least someembodiments.

FIG. 15 illustrates examples of connectivity verifier agents which maybe installed at customer guest virtual machines and at customer premisesfor use by a network health management service, according to at leastsome embodiments.

FIG. 16 illustrates examples of network pathways to customer datacenters, with respect to which metrics may be obtained by a networkhealth management service, according to at least some embodiments.

FIG. 17 illustrates an example system environment in which datacollected from network packet tracking sessions associated with anencapsulation protocol may be utilized by a network health monitoringservice, according to at least some embodiments.

FIG. 18 provides an overview of network packet flow using encapsulationbetween virtual machines instantiated at different virtualization hosts,according to at least some embodiments.

FIG. 19 illustrates example metrics which may be obtained with respectto a network packet tracking session, according to at least someembodiments.

FIG. 20 illustrates an example system environment in which, prior topresentation via a programmatic interface, network health stateinformation may be filtered based on anticipated customer impact ofimpairment events, according to at least some embodiments.

FIG. 21 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service, according to at leastsome embodiments.

FIG. 22 is a flow diagram illustrating aspects of an algorithm foraggregating and verifying network health information, according to atleast some embodiments.

FIG. 23 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which enables clientsto request network health state information via programmatic interfaces,according to at least some embodiments.

FIG. 24 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which providescustomizable graphical representations of network health stateinformation, according to at least some embodiments.

FIG. 25 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which filters networkhealth information based on customer impact, according to at least someembodiments.

FIG. 26 is a block diagram illustrating an example computing device thatmay be used in at least some embodiments.

While embodiments are described herein by way of example for severalembodiments and illustrative drawings, those skilled in the art willrecognize that embodiments are not limited to the embodiments ordrawings described. It should be understood, that the drawings anddetailed description thereto are not intended to limit embodiments tothe particular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope as defined by the appended claims. The headings usedherein are for organizational purposes only and are not meant to be usedto limit the scope of the description or the claims. As used throughoutthis application, the word “may” is used in a permissive sense (i.e.,meaning having the potential to), rather than the mandatory sense (i.e.,meaning must). Similarly, the words “include,” “including,” and“includes” mean including, but not limited to. When used in the claims,the term “or” is used as an inclusive or and not as an exclusive or. Forexample, the phrase “at least one of x, y, or z” means any one of x, y,and z, as well as any combination thereof.

DETAILED DESCRIPTION

Various embodiments of methods and apparatus for operations performed ata network health management service of a provider network, includingtechniques for aggregating metrics collected from a variety of sourcesat different granularities to produce customized and easy-to-understandnetwork health state information relevant to the particular sets ofresources allocated to customers, are described. The terms “networkhealth state” or “network health status” may be used herein to indicateinformation regarding the performance and availability of networkpathways between various types of resources, as described below infurther detail. Health state information may be provided at variouslevels of detail in different embodiments, e.g., based on customerpreferences. At a high level, an indication of whether a networkimpairment or failure has been detected with respect to certain sets ofresources, and if so the extent to which the impairment may be affectingany given customer or a particular customer may be provided in variousembodiments. At a more detailed level, statistics regarding packet lossrates, latencies (including aggregate statistics such as mean latency or90^(th) percentile latency for various packet sizes, and/or measures of“jitter” or latency variation over time), and the like may be provided,e.g., upon request, to customers in some embodiments.

Networks set up by an entity such as a company or a public sectororganization to provide one or more network-accessible services (such asvarious types of cloud-based computing or storage services) accessiblevia the Internet and/or other networks to a distributed set of clientsmay be termed provider networks herein. A provider network may sometimesbe referred to as a “public cloud” environment. The resources of aprovider network may in some cases be distributed across multiple datacenters, which in turn may be distributed among numerous geographicalregions (e.g., with each region corresponding to one or more cities,states or countries) and may be organized into availability containersor availability zones for failure resilience purposes as described belowin further detail. The underlying metrics to be used for network healthstate determination may be collected from data sources and/orintermediary tools at various levels of the provider network's resourcegrouping hierarchy—e.g., metrics may be collected indicative ofconnectivity or network performance between pairs of data centers,between pairs of availability containers, and so on.

In some provider networks, a multi-tenant virtualized computing servicemay be supported, as well as one or more multi-tenant storage services,database services, and the like. Using such services, customers may, forexample, acquire a set of virtual machines from the virtual computingservice, store various data sets at storage devices of selected storageservices, and use the virtual machines to run applications that accessthe data sets. A given resource (e.g., a storage device or a computingdevice) of a multi-tenant service may at least in principle be utilizedfor operations performed on behalf of multiple customer accounts. Ingeneral, in at least some provider networks, information aboutinfrastructure implementation details (e.g., the locations of varioushosts or servers which may be in use for a given client) may not beaccessible to customers; instead, customers may rely on the providernetwork operator to provision the appropriate set of physical and/orvirtual resources to meet customer needs. As such, at least some of theunderlying infrastructure components of the provider network, which maybe involved in providing connectivity between endpoints of interest tocustomers, may be considered “non-public”, and may not be visible to oraccessible to customers. In various embodiments, the network healthmanagement service may analyze metrics pertaining to non-publicresources or devices (e.g., routers, physical network links,virtualization management software and the like which may not beaccessible to customers), as well as from customer-visible data sources(such as processes running at virtual machines allocated to customers),to determine network health states for various endpoint pair categorieswhich may be relevant to a given customer.

The term “endpoint pair”, as used herein, may indicate a pair ofresources between which network packets may flow in one or bothdirections on behalf of one or more customers. For example, one endpointpair may include, as the first element of the pair, a guest virtualmachine established on behalf of a particular customer at avirtualization host of the provider network, and as the second element,a program running at a host located in a customer data center. Insteadof (or in addition to) providing network health state information at thelevel of individual resources, the network health management service mayprovide summarized information with respect to various categories ofendpoint pairs as discussed below in further detail. Thus, in the aboveexample, the network health management service may (at least initially)provide information about the state of the network paths between a groupof guest virtual machines established for the customer, and a group ofdevices located at the customer data center, instead of reporting on thestate of the network path between an individual guest virtual machineand an individual customer data center device. Each of the two endpointsrepresented in an endpoint pair category may thus represent a respectiveresource set (one resource set comprising the group of virtual machinesin the above example, and the other resource set comprising the group ofdevices located at the customer data center). The path between theendpoints of an endpoint pair category may comprise a virtualrepresentation of one or more physical network links and/or associatednetwork devices over which traffic flows between the correspondingresource sets in various embodiments. As such, the numerous devices andlinks of a potentially complex physical network being used on behalf ofa customer may be virtualized into one or more endpoint pair categoriesfor which easy-to-understand health state information can be provided.In some embodiments, detailed network health state information withrespect to specific endpoints or resources may also be provided. In someembodiments, customers may be able to specify or select the particularendpoint pair categories for which network health state information isdesired, and/or the particular endpoints for which network health stateinformation is desired.

In general, the network health management service may be designed toprovide relevant and reliable health state information efficiently tocustomers of various provider network services. “False positive” reportsof network impairment (i.e., reports of problems which either do notexist, or may exist but do not affect a particular customer to whom areport of a problem is provided), which may tend to alarm customersunnecessarily, may be avoided as much as possible in variousembodiments. Generally speaking, false positive reports may have severaldifferent root causes, including for example potentially unreliablemetrics or data sources, the inability to determine whether a givennetwork failure is actually going to impact a given customer, and so on;each of these types of causes may be addressed by the network healthmanagement service as described below in further detail. For example,prior to providing a potentially inaccurate report regarding a networkimpairment event, evidence of the event from multiple independentsources may be obtained in some embodiments. By providing timely andaccurate network health state information, the network health managementservice may make it easier for customers to quickly determine whetherunexpected application behavior is more likely to have been caused by aninfrastructure issue or by problems in the application itself, therebypotentially reducing debugging costs. In effect, the service may consumelarge volumes of network related metrics from a variety of sources, andtranslate the metrics into health state information which is potentiallymuch more useful to customers than the raw metrics may have been. Invarious embodiments, some of the raw metrics may not even be meaningfulto customers, as they may refer to internal resources and devices ofwhich customers are unaware. A number of easy-to-use programmaticinterfaces for obtaining the network health state information at desiredlevels of granularity and desired reporting frequencies may be supportedin different embodiments as described below. The network healthmanagement service (which may also be referred to as a network healthmanager herein) may in some embodiments be implemented as an independentservice with its own sets of programmatic interfaces; in otherembodiments, the network health management service may be subsumedwithin one of the other services of the provider network, such as avirtualized computing service. The network health management service mayin general comprise or utilize a plurality of hardware and/or softwarecomponents distributed within the provider network (and in some cases,outside the provider network, such as connectivity verification agentsinstalled at customer data centers, which are described below).

According to one embodiment, the network health manager may beconfigured to identify one or more endpoint pair categoriescorresponding to resources associated with a customer of a virtualizedcomputing service. The endpoint pair categories may be identified, forexample, based on interactions with control plane or administrativecomponents of the virtualized computing service at which resourceallocation inventories may be maintained. Depending on the needs of anindividual customer, one or more isolated virtual networks may beestablished for the customer as discussed below, and an endpoint paircategory may comprise a virtual machine within one of the isolatedvirtual networks in some embodiments.

Various sets of network metrics which may provide insight into thehealth of endpoint pair categories relevant to the customer may beobtained in different embodiments. For example, a first set of networkmetrics may be obtained from a connectivity verifier tool, while asecond set of network metrics may be obtained from an infrastructuremonitoring tool or service. The connectivity verifier may comprise afleet of agents or nodes which are configured to periodicallycommunicate with one another and/or with endpoints outside the providernetwork in some embodiments, including at least one agent instantiatedat a virtual machine established at the virtualized computing service.The agents may run as user-mode or application-layer processes in someembodiments, and as kernel-mode processes (or some combination ofuser-mode and kernel-mode components) in other embodiments. Theinfrastructure monitoring tool may collect metrics from at least somenon-public resources or devices, such as routers, physical networklinks, and the like, which are not accessible to customers directly.

In some embodiments, respective weights may be assigned to the networkmetrics sets (or, more broadly, to the tools from which the metric setsare obtained), indicative for example of the relative priority ortrustworthiness of the metrics sets with regard to potentialidentification of network impairments. For example, a knowledge baseaccessible to the network health manager may include entries indicatingthe reliability of various tools in different locations of the providernetworks, the number of times false positive reports of networkimpairment have been produced using data from individual tools orunderlying data sources, and so on. The factors taken into account whenassigning weights may include, for example, the physical locations fromwhich the metrics are collected, the logical location in thesoftware/hardware stack from which the metrics are collected, howrecently the metrics were collected (their collection times), and so onin various embodiments.

The network health manager may utilize the metrics sets and theirrespective weights to determine respective network health state ofdifferent endpoint pair categories, and provide an indication of thestate to one or more destinations associated with the customer. Forexample, in one embodiment, a request may be received for network healthstate information via a programmatic interface such as an API(application programming interface) exposed by the network healthmanagement service, and the requested information may be provided in aresponse to an API invocation. In another embodiment, a data set whichcan be used to display a graphical representation or layout of resourcesused by the client as well as the corresponding network health stateinformation may be transmitted to a client-side device for presentation.

In one embodiment, at least one metrics set collected by the networkhealth manager may indicate a possible network impairment event, such asa failure of a router, gateway, or a physical network link. In anattempt to reduce false positive reports of such impairments, thenetwork health manager may try to verify, using different metric setsobtained from another source, whether the impairment has actuallyoccurred. A verification algorithm that may rely on factors such as thenumber of independent sources which appear to confirm the impairment,the number of successive metrics sets which indicate impairment, therelative weights assigned to the metrics sets or their sources, and soon, may be used before the impairment is reported to a customer. In atleast one embodiments, fine-grained information about network packetflows, obtained for example at an encapsulation protocol processingcomponent of the provider network, may be used to filter reports ofnetwork impairment to only those customers whose applications areexpected to be affected by the impairments, as discussed below infurther detail. In one such embodiment, respective probabilities ofimpact of a network impairment event on a given customer'sapplication(s) may be assigned, e.g., based on an analysis of networkconfiguration of resources allocated to the customer and/or on theparticular services being used by the customer, and a report of theimpairment event may be provided to a customer if the probability ofimpact exceeds a threshold.

Example System Environment

FIG. 1 illustrates an example system environment in which metrics from avariety of data sources may be aggregated to provide network healthstate information to customers of one or more provider network servicesvia programmatic interfaces, according to at least some embodiments. Asshown, system 100 comprises a provider network 102 at which a number ofnetwork-accessible services may be implemented, including for example avirtualized computing service (VCS) 130, a storage service (SS) 140, anda database service (DS) 150. The VCS, SS and DS may each comprisevarious resources which are allocated for use by service clients, aswell as internal resources which are private to the service and areinaccessible to clients. For example, the VCS 130 may comprise aplurality of guest virtual machines (GVMs) 132, such as GVM 132A, 132Bor 132C, each of which may have been instantiated on behalf of a givencustomer of the VCS. Similarly, the storage service 140 may comprise aplurality of customer storage assets (CSAs) 142, such as CSA 142A and142B, while the database service 150 may comprise a plurality ofcustomer database assets (CDAs) 152, such as CDA 152A or 152B. A CSA 142may comprise, for example, an unstructured storage object accessible viaa web-services interface, a storage volume accessible via block-devicelevel interfaces, and so on. A CDA 152 may comprise, for example, aninstance of a relational database or a non-relational database, and soon. A given customer of the provider network may be allocated resourcesof a plurality of services in the depicted embodiment—for example,customer C1's resource set 172 may comprise GVMs 132B and 132C, CSA 142Aand CDA 152A as shown. In some embodiments, the provider network mayinclude other services which are not shown in FIG. 1, such as a machinelearning service, a parallel computing service, and so on, and a givencustomer's resource set may include resources from those other services

Each service may comprise a set of administrative or control-planecomponents, not shown in FIG. 1, which may maintain informationindicating the allotments or allocation of specific resources to variouscustomers as well as various other kinds of metadata. Such resourceallocation metadata may be queried in some embodiments by the networkhealth management service to determine the particular endpoint paircategories for which network health state information is to be providedto a particular customer, as discussed below in further detail. Inaddition, respective sets of service-specific private resources may beused to support the customer-facing functionality at each service, suchas private VCS resources 136, private storage service resources 146 andprivate database service resources 156. Some resources 158 (e.g.,various physical network links, internal routers of the providernetwork, etc.) may be shared by several different services, and hencemay be referred to as cross-service resources or multi-serviceresources.

The GVMs allocated to a given customer may be used to run variousapplications of the customer's choice in the depicted embodiment, andthose applications may communicate with and/or utilize resourcesimplemented using other services of the provider network 102, includingfor example the storage service and the database service. The dottedlines with double arrows indicate network packet pathways which may beused on behalf of service customers. For example, network packets mayflow between GVM 132B and CDA 152A, between GVM 132C and CSA 142A, andbetween GVM 132B and external endpoints 170 (such as devices of thepublic Internet and/or devices located at customer premises such asoffices or customer-managed data centers). GVM 132B and CDA 152A may beconsidered one endpoint pair whose network health state may be ofinterest to customer C1, GVM 132C and CSA 142A may be considered anotherendpoint pair, while GVM 132B and external endpoints 170 may beconsidered a third endpoint pair. More broadly, endpoint pair categoriesof interest may include {GVMs of VCS 130, CSAs of SS 140}, {GVMs of VCS130, CDAs of DS 150} and {GVMs of VCS 130, external endpoints 170}. Itis noted that at least in some embodiments in which one or more of theother services used by GVMs of VCS 130 (such as SS 140) allow accessfrom the public Internet, special endpoints called virtual privateendpoints may be established within the VCS to enable service requeststo flow from the VCS to the other services (and responses to the servicerequests to be received) without requiring the use of a public IPaddress or the use of public Internet links.

In the depicted embodiment, a network health management service (NHMS)110 comprising a plurality of nodes may be established at the providernetwork to provide network health state information regarding variousendpoint pair categories (and/or specific endpoint pairs) to clientssuch as 120A or 120B via a variety of programmatic interfaces 119. Theprogrammatic interfaces 119 may comprise, for example, a set of APIs forsending health state requests and receiving corresponding responses(e.g., requests/responses 166), one or more web-based consoles, one ormore command-line tools, and/or graphical user interfaces (GUIs) whichare not necessarily web-based. The NHMS 110 may include a plurality ofaggregation and analysis nodes (AANs) 112, such as AANs 112A and 112B,each of which may be implemented using one or more computing devices inthe depicted embodiment. In addition, metadata 113 used for aggregatingand presenting health state information may be maintained at the NHMS110, such as knowledge base entries which can be used to assign trustscores or weights to various metrics, client preferences, and so on.

The AANs 112 may be configured to identify the particular endpoint paircategories which correspond to a given customer's resource set in thedepicted embodiment, e.g., by querying one or more control-planemetadata stores associated with various services including the VCS 130,the SS 140 and/or the DS 150. The AANs 112 may collect a variety ofnetwork metrics sets from various parts of the provider network 102 inorder to provide relevant and reliable network health state informationto clients 120. A number of metrics collectors (MCs) may be used, suchas MCs 134 associated with VCS 130, MCs 144 associated with storageservice 140, MCs 154 associated with database service 150, and one ormore MCs 164 which are not specifically tied to any particular serviceof the provider network. In different embodiments, some MCs may comprisepre-existing tools that already collect various types of metrics, whileother MCs may represent agents (e.g., processes or threads of execution,or hardware devices) set up on behalf of the NHMS itself. Some MCs maycollect network metrics, such as request/response message success rates,from entities visible to customers, while other MCS may collect metricsfrom private resources such as resources 136, 146, 156 or 158. Ingeneral, as indicated by the non-dashed arrows in FIG. 1, networkmetrics information may flow from the underlying resources of theprovider network to the MCs, and from the MCs to the AANs in thedepicted embodiment. A preliminary level of aggregation or summarizationmay be performed at one or more of the MCs in at least some embodimentsbefore the metrics are passed on to the AANs. It is noted that some AANsmay collect network metrics from one or more source directly in at leastone embodiment, e.g., without utilizing intermediary MCs.

In some embodiments, respective sets of AANs 112 and MCs may be set upcorresponding to various hierarchical and/or location-based groupings ofservice resources. For example, as discussed below, in some embodiments,respective AANs and/or MCs may be set up in each room of each datacenter of the provider network at which resources used for a givenservice are located. Generally speaking, the NHMS 110 may be designed tobe able to detect network problems or impairments at various granularitylevels by combining information obtained from a wide range of datasources, so that the appropriate network health state information can beprovided quickly to clients 120.

The AANs may assign respective weights or trust scores to individual MCsand/or to individual metrics sets in the depicted embodiment, e.g.,based on a variety of factors such as the history of false positivereports of network impairments, the level of the data sources within thesoftware/hardware stacks, the locations of the data sources, etc. Usingthe weights and the collected metrics, respective descriptors or recordsindicative of the current (and/or past) network health state ofdifferent endpoint pair categories may be generated. In someembodiments, respective probabilities of a given network impairment'simpact on a given customer's applications may be estimated, and theindication of the impairment may be provided if the probability exceedsa threshold. In various embodiments, confirmations of the evidence whichindicates a potential network problem may be obtained from multiplesources, before presenting an indication of the problem to a client 120.The health state information pertaining to a given customer may beprovided via the appropriate sets of programmatic interfaces 119 to oneor more destinations in the depicted embodiment. In some embodiments, atleast some of the network health state information may be stored in arepository, e.g., for trend analysis, at least temporarily.

Intermediary Tools

FIG. 2 illustrates an example scenario in which output produced by avariety of intermediary tools may be used to generate network healthstate information, according to at least some embodiments. In thedepicted scenario, networking-related metrics generated at a variety ofdata sources 210 may be utilized, together with service use metadata270, to produce curated network health state information 260 for clients240 by one or more NHMS node(s) 230. The data sources may include, forexample, one or more GVMs (as in the case of data source 210A), one ormore network links (as in the case of data source 210E), and so on. Forsome data source categories, the provider network may have existingmetrics collectors available in the form of tools that may also be usedfor other control-plane functions. Such tools may be used asintermediaries 220 by the NHMS in the depicted embodiment. For example,a connectivity verifier tool 220A may obtain request/response messagesuccess rate metrics from a variety of GVMs in the depicted embodiment,while an infrastructure monitoring tool 220B may check the latencies andpacket drop rates across selected network links.

Network metrics may also be collected at the NHMS directly from at leastsome of the underlying data sources in various embodiments, as in thecase of data source 210K. It is noted that from the perspective of theNHMS nodes 230, the intermediary tools 220 may be considered datasources, even though the data being provided by the intermediary toolsmay in turn have been obtained from other resources. The intermediarytools 220 may each provide data in different formats, and the NHMS nodesmay be responsible for parsing the diverse data records provided,normalizing them into a standard format, disambiguating among theresources to which the metrics from different tools apply, mapping themetrics to different endpoint pair categories, and so on. Service usemetadata 270 may indicate the particular provider network services andfeatures which are being used by a given customer in the depictedembodiment, as well as the specific resources of each service which areallocated to the customer. The service use metadata 270 may be helpfulin identifying the particular endpoint categories for which networkhealth state information 260 should be provided to a given client 240.The network health state information 260 may be described as curated inthe depicted embodiment in that, for example, customized summaries ofrelevant information pertinent to individual client accounts may beprovided (rather than a generic representation of network health stateinformation applicable to an entire service or provider network). Insome cases, for example, even if two customers have resources located inthe same room of a particular data center, different health stateinformation may be provided to the two customers based on the specificservices being used and/or the differences in the networkingconfigurations of the resources.

Network Health Management Service Node Components

FIG. 3 illustrates example components of a network health managementservice node, according to at least some embodiments. As shown, networkhealth management service (NHMS) node 302 (which may correspond to anaggregation and analysis node 112 of FIG. 1) may comprise, for example,a client account resource set detector 304, one or more metrics recordsparsers 306, a data source disambiguator 308, a weight assigner 312, astate aggregator/verifier 314, and/or a presentation manager 316.Individual ones of the components shown in FIG. 3 may be implemented asseparate software processes or threads of execution in some embodiments.In at least one embodiment, some of the components may be implemented infirmware and/or in hardware.

The client account resource set detector 304 may determine, e.g., viacommunications with respective control plane (i.e., administrative)components 352 of one or more services of the provider network, thecollection of provider network services that are being used by (or havebeen allocated to) a customer associated with a given client account,and/or the specific resources of various services that are being used.As mentioned above, networking-related metrics may be collected at anNHMS node 302 from a variety of data sources. The metrics recordsobtained may be formatted differently by the various intermediary toolsand/or data sources, and parser(s) 306 may extract the relevantinformation from the metrics records. In at least some cases, metricspertaining to the same underlying network flow may be received from morethan one data source. For example, two application-layer processes atrespective hosts may provide respective packet loss rates with respectto network traffic between the hosts, while an intermediary networkdevice such as a router or switch may also provide information about thepackets transferred between the hosts. The data source disambiguator 308may be responsible for identifying, using any of variouscorrelation-based techniques, the specific underlying resources to whichone or more metrics sets correspond in the depicted embodiment. In someembodiments, various tools or data sources may express measurements ofthe same underlying phenomena in different units, and such measurementsmay be normalized to a common unit, e.g., by disambiguator 308 or byparsers 306.

Respective weights or trust scores may be assigned to metrics sets ordata sources which provide the metrics sets in the depicted embodiment.A number of different factors may be taken into account by weightassigner 312. For example, a knowledge base 354 may contain records 377indicative of the history of false positive reports regarding networkimpairments and the data sources or tools whose output was utilized forsuch reports. In addition, in some embodiments knowledge base 354 mayinclude data source location records 378 indicating the specific layersof the software/hardware/firmware stack from which networking-relatedmetrics are collected at various data sources, the physical orgeographical locations of various data sources, and so on. In someembodiments, the weight assigner 312 may also consider timing andrepetition-related factors 379—for example, if three consecutive metricssets obtained from a given data source or intermediary tool indicatethat a network impairment event may have occurred, the weight assignedto that data source or tool may be higher than if only two out of thelast five metrics sets obtained indicated the network impairment. Howrecently a given metrics set was received may also play a role—e.g., ifthe collection time of one metrics set MS1 was ten minutes in the past,while the collection time of a different metrics set MS2 was one minutein the part, MS1 may have a lower trust score or weight assigned thanMS2 (other factors being equal). In one implementation, the time thathas elapsed since a metric set was collected may be used as a decay term(e.g., a linear or exponential decay) in a function used to assignweights or trust scores.

State aggregator and verifier 314 may be responsible for combining theinformation contained in the metrics collected, together with theweights assigned to the metrics, and generating network health statesummaries and/or details for various endpoint pair categories (and/orpairs of specific endpoints). In various embodiments, the aggregatedinformation may be stored in the form of health state descriptors orrecords of the kind described below in the context of FIG. 4. A formulawhich adds weighted representations of the different metric setscorresponding to a given endpoint pair category and then normalizes thesum based on the number of different sources may be used in someembodiments to obtain a network health state summary for the category.In at least some embodiments, a probability or confidence level may alsobe assigned to the network health states—e.g., with respect to a givenendpoint pair category at a particular point in time, a 90% probabilitymay be assigned to a “no impairment” state, a 9% probability may beassigned to a “partial impairment” state, and a 1% probability may beassigned to an “extensive impairment” state. In one embodiment, theaggregator/verifier components may be configured to utilize a pluralityof metrics sets obtained from independent sources to verify certainkinds of network health states—e.g., a second or third tool or datasource may be used to confirm an apparent network impairment event.

The presentation manager 318 may be responsible for formatting networkhealth state information appropriately for transmission to variousdestinations. For example, the network health state for a set ofendpoint pairs may be presented in human-readable format for one set ofdestinations (such as email addresses of interested parties) and inmachine-readable format for another set of destinations (such as alertgenerator programs and the like). In at least one embodiment, data setsthat can be used to generate graphical representations of a customer'sresources and the corresponding health state information may be producedby presentation manager 318 and transmitted to one or more clientdisplay devices. Depending on preferences indicated by customers and/orsummarization decisions made at the NHMS, only a subset of the totalnetwork health information aggregated at node 302 (and recorded innetwork health state descriptors) may be transmitted at a given time orin a given message/report in some embodiments. It is noted that some ofthe components shown in FIG. 3 may not be implemented at one or moreNHMS nodes in some embodiments. In one embodiment, respective sets ofNHMS nodes may be designated for various functions—e.g., some nodes maybe responsible for metrics set collection and parsing, others for weightassignment, others for aggregation/verification of network health state,and others for formatting or presentation of the state information.

Health State Descriptor Elements

FIG. 4 illustrates example elements of a network health state descriptorwhich may be used to store information aggregated on behalf of acustomer, according to at least some embodiments. Such descriptors maybe prepared and/or stored by NHMS nodes, and subsets (or all) of thecontents of the descriptors may be used to provide network health statereports or results to client destinations. As shown, a given healthstate descriptor 402 may include, among other elements, a clientidentifier 403, an endpoint pair category 404 to which the descriptorapplies, a timestamp or time period 406, an impairment-related summarystate 408, request/response success statistics 410, latency statistics412, packet loss rate statistics 414, trend information 416, and/oridentifiers 418 of the particular data sources or tools used for theinformation contained in the descriptor.

Client identifier 403 may indicate, for example, a client account of theprovider network on whose behalf the network state information stored inthe remainder of the descriptor 402 is being generated. As mentionedearlier, in various embodiments the set of endpoint pair categories withrespect to which network health state information is to be provided fora given customer may be determined at the NHMS. Examples of severalendpoint pair categories are discussed in further detail below in thecontext of FIG. 9. In the depicted embodiment, a respective descriptor402 may be generated periodically for individual endpoint paircategories. In other embodiments, network health state informationpertaining to multiple endpoint pair categories may be stored within asingle descriptor.

The timestamp or time period element 406 may indicate the time at which(or the time period during which) the metrics used to generate thehealth state information were collected in the depicted embodiment. Theimpairment-related summary state 408 may provide a high-level overviewof packet flow conditions via network pathways between the endpointpairs represented by category 404. The summary state for a givenendpoint pair category may be selected from a (typically small) set ofoptions in various embodiments, e.g., in which an individual option mayrepresent a corresponding degree of impairment of network trafficassociated with the endpoint pair category. In one embodiment, acolor-coded scheme may be used (e.g., at a client-side display device atwhich a data set derived from descriptor 402 may be displayed) toindicate the severity of an impairment, in which the color green or theword green indicates unimpaired connectivity (packets are flowingwithout significant errors or delays), the color or word yellowindicates partial impairment of connectivity (some packets may bedropped/delayed between some endpoints), while the color or word redindicates severe impairment of connectivity (most packets may be delayedor dropped). Other symbols or encodings of the high-levelimpairment-related summary state 408 may be used in other embodiments.For example, numeric codes may be used in some embodiments: e.g., “0”for no impairment, “1” for partial impairment, and “2” forsevere/extensive impairment, or a “percent impaired” scheme may be used,in which the probability of encountering a problem due to an impairmentis provided (e.g., based on an approximate fraction of resources of aparticular type which are impacted by a failure event). In variousembodiments the network health management service may define a defaultset of impairment-related summary states for various types of endpointsand resources, e.g., based on respective ranges of metrics. In at leastone embodiment, as discussed below in the context of FIG. 5, customersmay specify their own definitions of at least some health states, whichmay override the default definitions.

A number of lower-level statistics may be used to derive the summarystate in different embodiments, and at least some of the lower-levelstatistics may be stored in the descriptor 402 in the depictedembodiment. Request/response success rate statistics 410 may begenerated, for example, by a connectivity verifier tool which causesrequest messages from selected agents to be sent to selected endpointsand tracks how many responses to the request messages are receivedwithin a threshold interval. Latency statistics 412 may record the timetaken for messages to be transmitted from one device to another.Different kinds of latency statistics 412 may be collected and/orprovided to clients of the network health management service, indifferent embodiments. For example, aggregate statistics such as meanlatency for different packet sizes may be collected in oneimplementation, while jitter statistics indicating variations inlatencies over time may also or instead be collected in anotherembodiment. Packet loss rate statistics 414 may indicate the fraction ofpackets that were lost or dropped during a given period of networktraffic between two endpoints. Individual ones of the statistics 410,412 and 414 may be computed or aggregated using metrics collected fromvarious data sources in the depicted embodiment. In some embodiments,information 416 regarding recent trends in some or all of the otherstatistics may be stored in a descriptor 402. In at least oneembodiment, an indication of the particular tools or data sources fromwhose output the statistics and/or summary were derived may also bestored in a descriptor 402, e.g., using ID element 418. It is noted thatonly a subset of the information indicated in the descriptor 402 may beprovided to clients of the network health management service in variousembodiments—e.g., in one embodiment, at least initially, only thesummary information may be provided to clients via a programmaticinterface. Some programmatic interfaces may enable clients to obtainmore details, such as the statistics 410, 412 or 414, and/or the trendinformation 416. In at least one embodiment, descriptors 402 may notnecessarily be stored in persistent storage. A given descriptor 402 maysimply represent the intermediate results of processing some set ofnetwork health-related metrics on behalf of a customer, prior toreporting health state information derived from the metrics to thecustomer.

Health State Request Elements

FIG. 5 illustrates example elements of a network health state requestwhich may be transmitted via a programmatic interface supported by anetwork health management service, according to at least someembodiments. As shown, a request 502 may include an indication of one ormore client identifiers 504, a list of targeted resources or services506, one or more endpoint pair categories 508, a time period 510, healthstate definitions 512, reporting threshold(s) 514, areporting/notification mechanism 516, a reporting format 518 andretention settings 520 in the depicted embodiment.

A given customer of a provider network may be associated with severalclient accounts in some embodiments—e.g., different accounts may havebeen set up for different departments of an organization, or fordifferent collaborating business entities. The set of client accountsfor which network health state information is desired may be indicatedin client ID field 504. In some embodiments, customers with a largenumber of resources may only wish to see health state informationpertaining to a subset of the resources and/or services which they areutilizing; these resources and/or services may be indicated in element506 of the request 502.

In one embodiment, instead of or in addition to indicating the servicesand/or resources for which network health state information is to beprovided, a client may specify one or more endpoint pair categories 508.In some embodiments, a catalog of endpoint pair categories for whichhealth state information is available may be made available to customersvia a programmatic interface, and categories 508 may be selected fromsuch a catalog. In one embodiment, customers may define customizedendpoint pair categories, e.g., using labels of the kind discussed belowin the context of FIG. 9, and indicate such custom categories in element508. A time period over which metrics are to be collected or examinedmay be indicated in element 510 of the request 502 in some embodiments.The time period may be expressed in either absolute or relativeterms—e.g., a client request may indicate the logical equivalent of “usemetrics corresponding to the most recent 10-minute period”, or “usemetrics collected between 17:00:00 GMT and 17:20:00 on Apr. 3 2016”. Thetime period element 510 may be used to obtain health state informationfor time periods in the past in some embodiments—e.g., to help performpost-event analysis of an application problem.

In at least some embodiments, clients may optionally indicatedefinitions 512 for a number of health states which the network healthmanagement service is to report with respect to the client's resources.For example, some clients may define a “severely impaired” state ifthere is a 10% probability of packets between a pair of endpoints beingdropped, while other clients may define a “severely impaired” state ifthe average latency of messages between a pair of endpoints exceeds Tmilliseconds, or if the jitter or variance of latencies exceeds athreshold. In some cases, health states may be defined using multipletypes of metrics. For example, a given state may be defined as a Booleancombination of a latency condition Cond1 and a packet drop ratecondition Cond2. In one such scenario, an unimpaired health state may bedefined by the logical equivalent of the Boolean combination “90^(th)percentile latency for P-byte packets is less than T1 milliseconds” AND“packet drop rate in the last M minutes is no greater than D percent”.The number of states defined by one client may differ from the numberdefined by another client. In some embodiments, different statedefinitions may be indicated for respective categories of resources orendpoints. Furthermore, in addition to the overall impairment-relatedstate (e.g., “unimpaired”, “severely impaired” etc.), in at least oneembodiment clients may wish to obtain the underlying metrics which ledto the determination of the overall state The kinds of metrics which areto be included in the response to request 502 may also be indicated inthe request in some embodiments (e.g., as part of the state definitionselement or in a separate element). Some clients may indicate thatimpairment-related summary state information of the kind discussed inthe context of element 408 of FIG. 4 is sufficient, while other clientsmay wish to obtain more detailed statistics regarding request/responsesuccess rates, packet drops, mean or percentile latency, latencyvariation (jitter) statistics and the like.

The reporting threshold 514 may be used to indicate the conditions underwhich a client is to be provided health state information. For example,some clients may prefer not to be provided health state informationunless there is a 10% probability of a network impairment event which islikely to impact the client's applications. Other clients may wish toreceive health state information regardless of whether an impairmentevent has been detected or not, or only when the state of a givenresource or endpoint pair changes. Any combination of a number ofreporting or notification mechanisms 516 may be indicated by a client inrequest 502 in various embodiments. For example, some clients mayindicate e-mail addresses, text message addresses or the like, whileother clients may wish to receive health state information on adashboard or graphical display. In some embodiments, a notificationservice of the provider network may be selectable as a notificationmechanism, or a client may simply want information to be provided via anapplication programming interface. Some clients may wish to use a “pull”model for obtaining network health state, in which the information isprovided only when requested, while others may prefer a “push” approach,in which the network health management service proactively sends healthstate information periodically or under specified conditions to one ormore destinations. A subscription model may be supported in at leastsome embodiments, in which in response to a single subscription request,multiple health state messages may be transmitted to one or moresubscribers using a specified notification mechanism, which each messageindicating the health state of one or more endpoint pair categoriesduring respective time intervals. Reporting format 518 may indicate theencoding or data structure to be used to report the health state in thedepicted embodiment—e.g., whether JSON (JavaScript Object Notation), XML(Extended Markup Language), or plain text is to be used, or whether ahash map or other data structure is to be used. Retention preferences520 may indicate a time period (e.g., a week or a month) for which thenetwork health state data is to be retained at the network healthmanagement service in some embodiments, e.g., so that queries regardingpast health states can be supported. In at least some embodiments, atime series format for reporting health state information may also besupported. A sequence of network health state data records may beprovided for an endpoint pair category or for a specific resource insuch embodiments, with each record corresponding to a respective pointin time within a time interval indicated by the client or selected bythe service (e.g., one record may be provided for each minute of theprevious ten minutes). Each network health state data record of a timeseries may represent a summary health state as of the correspondingpoint in time, or a particular metric collected at the correspondingpoint in time. In some embodiments, clients may request that informationabout various kinds of changes to health states of one or more endpointpair categories over time be provided. For example, instead of providinga static health state information report corresponding to a particulartime, or a time series whose intra-record intervals are explicitlyspecified by the customer, the NHMS may provide an indication of changesto the degree of impairment of an endpoint pair category over severalseconds or minutes. For example, the NHMS may report that an endpointpair was 70% impaired at time T1, 50% impaired at time (T1+delta1) asrepairs were performed, 20% impaired at time (T1+delta1+delta2), etc.Retention preferences 520 may be set in some embodiments based at leastin part on the desired time series durations and/or the time periodsover which changing health state information is to be reported.

In some embodiments, one or more APIs may be implemented by the networkhealth management service to enable health state requests to be sent tothe network health management service and to receive the correspondingresponses. For example, an API such as getHealthState(myAccountID,resourceDescriptor, serviceDescriptor, endpointPairDescriptor,timingPreferences, healthStateDefinitions, reportingThreshold,reportingMechanism, format, retentionPeriod) may be used in oneembodiment, with the parameters respectively representing the variouselements of request 502 shown in FIG. 5. Some or all of the parametersof getHealthState may be optional in various implementations—forexample, the account identifier of the customer may be inferred from aheader of the message used to submit the request, the network healthmanagement service may determine the resources/services targeted if theresourceDescriptor or serviceDescriptor parameters are not specified,and so on. In at least one embodiment, if and when a client submits theequivalent of “getHealthState( )” with no parameters, the network healthmanagement service may determine appropriate values for some or all ofthe elements shown in FIG. 2, e.g., using a set of default parameterdetermination algorithms and metadata obtained from various services,and provide meaningful health state information to the client based onthose values. It is noted that a request similar to that indicated inFIG. 5 may be generated as a result of a use of a graphical userinterface control (such as a mouse click on a button or a link) in someembodiments.

Data Source Examples

FIG. 6 illustrates example data sources from which networking-relatedmetrics pertaining to guest virtual machines of a virtualized computingservice may be obtained, according to at least some embodiments. Asdiscussed earlier, a virtualized computing service (VCS) may comprise aplurality of virtualization hosts, at individual ones of which one ormore guest virtual machines (GVMs) may be instantiated. In theembodiment depicted in FIG. 6, a virtualization host 602 of a VCScomprises two guest virtual machines 650A and 650B, as well as anadministrative virtual machine 655, a hypervisor 620, and a number ofhardware devices including CPUs 605A and 605B, main memory 608,virtualization management offload cards 610, and network interface cards(NICs) 611.

The administrative virtual machine 655, the hypervisor 620, and thevirtualization management offload cards 610 may collectively be referredto as virtualization management components (VMCs). The VMCs may act asintermediaries between the GVMs 650 and the (remaining) hardwarecomponents of the virtualization host, in effect presenting anabstracted or virtualized view of the hardware to each GVM. As discussedbelow in further detail, an encapsulation protocol may be implemented atthe VCS, which enables GVMs 650 to communicate with each other (and withother endpoints) using network addresses which are not tied to the NICs611 at the virtualization hosts.

Each GVM 650 (as well as the administrative VM 655) may comprise one ormore applications, such as customer applications 654A and 654B of GVMs650A and 650B respectively and administrative applications 657 of VM655, at least some of which may be communicating with applications atother GVMs, VCS hosts, endpoints of other services of the providernetwork, or endpoints outside the provider network. In addition, eachvirtual machine may comprise a respective operating system 652 (such as652A-652C) and may store respective networking-related configurationsettings 653 (e.g., 653A-653C).

The NICs 611 of the virtualization host 602 may be connected viaphysical links 661A to switches 628, which may in turn be connected viaadditional physical links 661B and 661C to routers/gateways 629 and/orother network devices 631. At least in principle, connectivitydisruptions, traffic flow slowdowns, packet drops and other networkimpairments may occur as a result of underlying problems at anycombination of the hardware and software components shown in FIG. 6.Furthermore, in some cases network impairments may result frominappropriate configuration settings 653. As a result, to obtain acomprehensive view of network health state of the GVMs allocated todifferent customers, in some embodiments respective metrics collectors634 may be set up to capture metrics from each of the different kinds ofcomponents shown, and pass the collected metrics on to the networkhealth management service. Some metrics collectors may be incorporatedwithin the virtualization hosts (e.g., as daemons or user-modeprocesses), while others may be external to the virtualization hosts(e.g., in the form of packet header analyzers, sniffers, traffic flowanalyzers, tapping tools, etc.). In some embodiments, one or more of themetrics collectors may periodically capture various configurationsettings 653 and provide them to the network health management servicefor analysis.

Resource Grouping Hierarchy

The complexity of determining the network health state of a customer'sresources may be further complicated by the fact that the resources maybe spread across widely distributed locations, potentially with somelocations more thoroughly instrumented for network measurements thanothers. FIG. 7 illustrates an example hierarchy of resources of avirtualized computing service, according to at least some embodiments.As shown, the resources of a VCS 702 may be dispersed among a pluralityof regions 712, such as regions 712A and 712B. A given region may 712may comprise a group of data centers 716 (e.g., data centers 716A, 716Band 716G of region 712A, or data centers 716C and 716D of region 712B).The data centers which make up a given region may be located near toeach other, e.g., within the same metropolitan area or state, althoughthe correspondence between VCS region boundaries andgeographical/political boundaries may not be exact in at least someembodiments.

In the depicted embodiment, the VCS resources may also be logicallydivided among availability containers (ACs) 714, such as ACs 714A and714B of region 712A, and ACs 714C and 714D of region 712B. Availabilitycontainers may also be called availability zones in some environments. Agiven availability container may comprise portions or all of one or moredistinct locations or data centers, engineered in such a way (e.g., withindependent infrastructure components such as power-related equipment,cooling equipment, or physical security components) that the resourcesin a given availability container are insulated from failures in otheravailability containers. In the examples shown in FIG. 7, ACs 714A, 714Cand 714D each comprise resources within a single data center, while theresources of AC 714B span two data centers 712B and 712G. A failure inone availability container may not be expected to result in a failure inany other availability container; thus, the availability profile of agiven resource is intended to be independent of the availability profileof resources in a different availability container. Various types ofservices and/or applications may therefore be protected from failures ata single location by launching multiple application instances inrespective availability containers. As discussed below in furtherdetail, an isolated virtual network comprising GVMs in multipleavailability containers may be set up on behalf of some VCS customers toenhance the failure resilience of the customer applications. From theperspective of application availability, information about the state ofthe network pathways between availability containers may be especiallyimportant to at least some customers.

Each data center 712 may in turn comprise one or more rooms, such asroom 722A of data center 712B. A given room may in turn comprise aplurality of racks, such as rack 724A, within which a number ofvirtualization hosts (such as virtualization host 726A of rack 724A) arelocated, and each virtualization host may comprise zero or more GVMs(such as GVM 728A of host 726A). Networking failures or otherimpairments may occur at any of the various levels of the hierarchyshown in FIG. 7. In some embodiments, nodes of the network healthmanagement service may also be organized hierarchically. For example,one or more region-level NHMS nodes 720 (e.g., 720A or 720B) may beestablished in each region, AC-level NHMS nodes 740 (e.g., 740A-740D)may be set up in each availability container, data center level NHMSnodes 718 (e.g., 718A, 718B, 718G, 718C or 718D) may be configured ineach data center, and so on. At some levels of the hierarchy, metricscollectors and aggregation/analysis nodes may both be configured in oneembodiment, while at other levels, only metrics collectors or onlyaggregation/analysis nodes may be set up. In at least some embodiments,the hierarchy of the NHMS nodes may extend to other levels as well—e.g.,each rack may have its own NHMS node(s), or each room within a datacenter may have its own NHMS node(s). In the embodiment depicted in FIG.7, the NHMS may be responsible for translating large volumes of detailedpoint-to-point network metrics obtained at various levels of thehierarchy into reliable aggregated network health state informationwhich can be used by customers to diagnose and resolvenetworking-related problems of complex distributed applications asneeded.

Isolated Virtual Networks

Depending on their application and security needs, customers ofvirtualized computing service may require varying levels of networkisolation. FIG. 8 illustrates examples of isolated virtual networkswhich may be established on behalf of customers of a virtualizedcomputing service, according to at least some embodiments. The VCS 802comprises at least four availability containers (ACs) 814 in thedepicted embodiment—ACs 814A-814D. Four examples of isolated virtualnetworks (IVNs) 804 are shown—IVNs 804A, 804B and 804C, all establishedfor one customer C1, and IVN 804B, established for a different customerC2. IVN 804A comprises GVMs 816F, 816J and 816M, each of which is partof a respective availability container 814. IVN 804B comprises two GVMsin each of two ACs—GVMs 816D and 816E in AC 814B, and GVMs 816G and 816Hin AC 814C. IVN 804C comprises GVMs 816C and 816T, both of which arepart of AC 814A. IVN 804D comprises GVMs 816A and 816B in AC 814A, andGVMs 816K and 816L in AC 814D.

Generally speaking, an IVN 804 may comprise one or more guest virtualmachines and/or other devices (such as storage devices managed by astorage service, or networking devices such as virtual or physicalgateways) and resources of a provider network. The customer for whom theIVN is established may be granted substantial networking configurationflexibility for the IVN. For example, customers may choose a range ofprivate IP addresses from which particular addresses are to be assignedto various guest virtual machines, set up subnets, establish securityrules for incoming and outgoing traffic, create routing table entries,and so on, in a manner very similar to the way that networkconfiguration settings could be selected at a customer-owned facility.The private IP addresses assigned within a given IVN 804 may not beaccessible (at least by default) outside that IVN; as a result, theclient may choose arbitrary IP addresses for the GVMs without having tobe concerned about the possibility of duplicating addresses alreadyassigned outside the IVN. In general, IVN capability may enable VCSclients to set up networking configurations as though they were usingclient-owned resources, while benefiting from the scaling, availabilityand pricing-related advantages made possible by the provider network.IVNs may also be referred to as “virtual private clouds” in someprovider network environments.

In some embodiments, each of the GVMs allocated to a customer may belongto an IVN; in other embodiments, at least some GVMs which are notconfigured as part of an IVN may be assigned to a customer. DifferentIVNs may be used for respective groups of related applications, andsecurity settings may be configured independently for each IVN in someembodiments. By default, at least some of the resources (such as GVMs)within a given IVN may not be accessible to resources outside the IVN.In some embodiments, connectivity between the resources of an IVN, andresources outside the IVN, may be enabled using virtual and/or physicalgateways. Some IVNs may be configured to enable secure communicationsbetween the GVMs of the IVNs and networks outside the provider network,e.g., customer networks established at customer-owned data centers. Inat least some embodiments, IVNs may represent an important resourcegrouping abstraction from a customer perspective. As such, at least somecustomers may wish to obtain network health state information at the IVNlevel in such embodiments.

Endpoint Pair Categories

As mentioned earlier, in at least some embodiments, network health stateinformation may be generated with respect to a number of endpoint paircategories. FIG. 9 illustrates examples of endpoint pair categories forwhich respective health state information reports may be provided toclients of a network health management service, according to at leastsome embodiments. Each endpoint of an endpoint pair category mayrepresent a resource set with some set of characteristics in common invarious embodiments—e.g., the resources in a given resource set may havea common geographical location or network configuration setting, or theresources in a given resource set may be used for implementing aparticular service. The path between the endpoints of a given categorymay comprise a virtual representation of one or more physical networklinks, and the health state information for the category may be derivedat least in part using network metrics obtained from physical networkdevices used for traffic associated with the category.

Endpoint pair category 920A corresponds to resource sets located indifferent regions—e.g., one resource 912A in region R1, and anotherresource 912B in region R2. Category 920B comprises endpoints located indifferent availability containers—e.g., one resource 914A inavailability container AC1, and a second resource 914B in a differentavailability container AC2. Category 920C comprises endpoints located indifferent isolated virtual networks, such as a guest virtual machineGVM1 in isolated virtual network IVN1, and a second GVM, GVM2, in IVN2.

In category 920D, one of the endpoints is a public Internet resource918B (e.g., a web site of the public Internet), while the other endpointis a GVM (GVM1) within an IVN (IVN1) of the VCS. In category 920E, oneof the endpoints 930B corresponds to a resource which is part of acustomer-premise network, while the second endpoint is a resource (GVM1)within an IVN (IVN1) of the VCS. Endpoint pair category 920E representscross-service network traffic, e.g., between resource 932A of oneprovider network service (such as the VCS) and resource 932B of anotherprovider network service (such as a storage service or a databaseservice). As mentioned earlier, in some embodiments one or more of theother services accessed by GVMs of the VCS 130 may allow clients tosubmit requests from the public Internet. In some such embodiments,special endpoints (called virtual private endpoints) may be establishedwithin the VCS which enable service requests to flow from the VCS to theother services (and responses to the service requests to be received)using provider network resources, without requiring packets representingthe requests/responses to traverse the public Internet. An endpoint paircategory for cross-service traffic (analogous to category 920E) mayinclude a virtual private endpoint for one of the services as one of theendpoints of the pair in some embodiments.

In at least one embodiment, customers of the provider network may definecustom endpoint pair categories. For example, a set of APIs or otherprogrammatic interfaces may be provided to allow a customer to labelselected sets of resources with respective labels, and then to define anendpoint pair category which comprises one resource with one label, andanother resource with a different label. Consider one example scenarioin which a customer C1 has two applications, App1 (which runs on a firstset of VCS resources) and App2 (which runs on a different group of VCSresources). Using programmatic interfaces provided by the VCS or thenetwork health management service, customer C1 may label the resourcesbeing used for App1 as “App1-group” resources, and the resources beingused for App2 as “App2-group” resources. A custom endpoint pair categorysuch as 920G may then be created, corresponding to networkcommunications between resources of App1-group and App2-group. Othercustom endpoint pair categories may represent intra-group traffic—e.g.,App1-group resources communicating with other App1-group resources, orApp2-group resources communicating with App2-group resources. Networkhealth state information for the custom endpoint pair categories may beprovided to customer C1, e.g., either upon request or by default by thenetwork health management service. Some customers may wish to obtainnetwork health state information pertaining to a combination of customendpoints and service-defined endpoints. The paths 922 (e.g., paths922A-922G) between the endpoints of various endpoint pair categories maypresent a concise virtualized view of the various hardware components(e.g., physical network links, networking devices such as routers andthe like) and associated software/firmware used for the traffic betweenthe resources corresponding to the endpoints of the category. In effect,a virtualized view of the set of networking components being used onbehalf of a customer may be provided using endpoint pair categories invarious embodiments. Endpoint pair categories other than (or in additionto) those shown in FIG. 9 may be used in some embodiments. It is notedthat in various embodiments, the resources for which health stateinformation is provided to a given customer may in some cases be mappedto a single endpoint pair category; thus, multiple endpoint paircategories may not be identified for at least some customers.

In various embodiments, the network health management service may beresponsible for (a) identifying the endpoint pair categories for whichnetwork health state information is to be provided to a given client orcustomer and (b) using the network metrics obtained from various datasources and/or intermediate tools to generate network health stateinformation for the identified endpoint pair categories. In someembodiments, as mentioned earlier, control plane components of variousservices of the provider network may be able to indicate the kinds ofresources allocated to a given customer, from which the endpoint paircategories likely to be most useful to the customer may be derived. Inat least one embodiment, clients may specify the particular endpointpair categories for which health state information is desired, orclients may create new endpoint pair categories similar to category 920Gof FIG. 9, which may be assumed to be categories for which health stateinformation should be provided. Given the wide variety of data sourcesand metrics collectable in a large provider network environment, thetask of determining health state reliably for individual endpoint paircategories may involve the use of a variety of algorithms forcorrelation, disambiguation, verification and summarization. Forexample, information which may be pertinent to the health state ofendpoint pair category 920B (with endpoints in respective availabilitycontainers) may be received from a variety of sources such asapplication-level or user-mode connectivity verifiers, network linkmonitors, routers, encapsulation protocol processing components, and thelike. The information may have to be parsed and correlated (in terms oftime, in terms of physical and network locations of the resourcesinvolved, and so on). In some cases one part of the information obtainedmay conflict with another part, and a verification protocol (which mayinvolve gathering of additional data) may be used to resolve suchconflicts in various embodiments, before a summarized representation ofhealth state for the endpoint pair category can be generated.

Graphical Interface Examples

A variety of programmatic interfaces may be used to provide networkhealth state information at customizable granularity in variousembodiments, including for example web-based consoles, APIs, commandline tools and graphical user interfaces. FIG. 10 illustrates an examplegraphical interface which may be used to provide high-level networkhealth state information to a client of a virtualized computing service,according to at least some embodiments. As shown, the interface maycomprise a web-based health console 1002. The console 1002 may include amessage area 1003 providing an overview of the contents of the console,and a summarized representation 1010 of the portion of the network forwhich health state information is being displayed. Groups of resourcescorresponding to the endpoints of different endpoint pair categories maybe represented in summary form using individual icons, and the physicalnetworking links/devices between the groups of resources may berepresented by virtual paths between the endpoints of the categories. Inat least one embodiment, as soon as the network health managementservice detects that an entity associated with a client account hassuccessfully logged in to a management console associated with thevirtualized computing service (or some other service of the providernetwork), health state information similar to that shown in FIG. 10 maybe displayed (and the display may subsequently be refreshedperiodically). That is, logging in to the management console may serveas the equivalent of transmitting a request for graphical display ofnetwork health state (so that an explicit request for the graphicaldisplay of health state information may not be required). In oneimplementation, the health state information may be associated with onetab of several tabs of the management console—e.g., one tab may providebilling information, another may provide account profile information,another may be used to request resource allocations, while another mayprovide network health state information.

In the depicted example scenario, the console shows health stateinformation for several endpoint pair categories, with at least oneendpoint of each pair being a GVM within an isolated virtual networkIVN-K. The endpoint pair categories are labeled 1051-1060 in FIG. 10.Each endpoint pair category shown represents a type of network trafficflow over some collection of pathways for which summary health stateinformation may have been generated by aggregating metrics correspondingto a variety of data sources and locations. The GVMs of IVN-K aredistributed among two availability containers, 1011A and 1011B. One ofthree symbols indicated in legend 1006, each of which is indicative of arespective degree of impairment of network traffic, is assigned to eachendpoint pair category to summarize the network health state: the circlewith a check mark symbol indicates an unimpaired state, the circle withan “X” indicates severe impairment, while the circle with a “?”indicates partial impairment. In some embodiments, the severity of anetwork health problem or impairment may be indicated using a colorcode—e.g., a red icon or red text may be used to indicate extreme orsever impairment, a yellow icon or text may be used to indicate moderateor partial impairment, and a green icon or text may be used to indicateunimpaired state. Other encoding schemes to indicate degrees ofimpairment of network traffic corresponding to different network healthstates may be used in some embodiments. Buttons labeled “R-S” are shownadjacent to health state symbols which indicate impairment (eitherpartial or severe impairment), and may be used to obtain repair statusregarding the impairments. The definitions of each of the health states(that is, the conditions under which the state is deemed to beunimpaired, partially impaired or severely impaired) may be selected bythe network health management service in various embodiments. In atleast one embodiment, customers may provide their own customizeddefinitions for health states to the network health management service,and the service may use those definitions when reporting network healthfor the customers' resources.

One endpoint of endpoint pair category (EPC) 1053 represents GVMs ofIVN-K in availability container 1011A, while the other endpointrepresents GVMs of IVN-K in availability container 1011B. EPCs 1051 and1052 represent communications between the GVMs in availabilitycontainers 1011 and the external Internet. EPC 1057 represents networktraffic among the GVMs of IVN-K within availability container 1011A,while EPC 1158 represents network traffic among the GVMs of IVN-K withinavailability container 1011B.

In the depicted example, EPC 1054 represents traffic between the GVMs inAC 1001A and a customer-owned data center DC1, while EPC 1055 representstraffic between the GVMs in AC 1011B and a different customer-owned datacenter DC2, EPC 1056 represents traffic between IVN-K and anotherisolated virtual network IVN-L. EPC 1059 represents traffic between theGVMs of AC 1011A and a storage service SS1. EPC 1060 represents trafficbetween the GVMs of AC 1011B and a database service DS1.

Among the various endpoint pair categories for which health state isdisplayed in FIG. 10, one (EPC 1059) is in a severely impaired state,one (EPC 1052) is in a partially impaired state, and the remaining arein unimpaired state as of the time indicated in message area 1003. Zoomcontrols 1004 may be used to obtain more detailed network health stateinformation, as discussed below in the context of FIG. 11.

The kind of graphical display illustrated in FIG. 10, which in effectprovides a “virtual network” representation of the resources being usedfor a client, may be generated in response to a health state requestsubmitted by a client in various embodiments. The term “virtual network”may be used because information about at least some physical devices andphysical network links actually being used for the client's networktraffic may be abstracted in the form of icons and virtual pathscorresponding to endpoint pair categories. The particular focus of thedisplay (the GVMs of IVN-K in the illustrated example) may be indicatedin the request, or may be selected by the network health managementservice in various embodiments based on an examination of the resourcesbeing used by the requester. In at least some embodiments, a givenclient may have a large number of resources (e.g., dozens of IVNsdistributed among numerous regions and availability containers), and thenetwork health management service may have to determine how best tosummarize the state of the client's network given a limited amount ofdisplay space. The scale or granularity-related decisions for displayingcustomer network health information may be based at least in part oncharacteristics of the display—for example, it may be possible for thenetwork health management service to determine the size (in pixels) ofthe display device being used, and the granularity of the displayedinformation may be adjusted accordingly. In at least some embodiments,the information displayed via console 1002 may be refreshedautomatically, e.g., at a rate controllable via refresh control 1007.Note that, as new resources are allocated on behalf of the customer orsome resources are de-allocated, a subsequent refresh may result in thedisplay of health state information for a different set of endpoint paircategories—that is, either the set of endpoint pair categories, thestates of the pathways between the endpoint pair members, or both maychange over time.

In at least some embodiments, customers may provide feedback regardingthe network health state information displayed via the console 1002 (or,more generally, the health state information provided via any of thesupported interfaces). Such feedback may include, for example,confirmations indicating that the customer is experiencing applicationbehavior which matches the indicated health state information for anendpoint pair category or a particular resource, or contradictions ofthe health state indications provided by the network health managementservice. In the embodiment depicted in FIG. 10, the feedback may beprovided using control 1091 (which may lead to the display of a pop-uptext form or graphical input panel, for example). In other embodiments,at least some of the health state icons may have embedded controls whichenable a customer to provide feedback by clicking on or near the iconitself—e.g., with by clicking on the icon associated with EPC 1059,which shows extensive impairment, a customer may be able to confirm theimpaired state (or, in contrast, indicate that from the customerperspective, impairment is not being experienced with respect to networktraffic for EPC 1059). Such feedback messages may be provided vianon-graphical interfaces as well in some embodiments. For example, acustomer may receive a response to a network health state requestsimilar to that shown in FIG. 5 submitted via an API, and use anotherAPI to submit follow-up feedback indicating confirmation/contradictionof network health state information contained in the response. Otherinterfaces such as command-line tools may also be used in variousembodiments for feedback messages.

Contents of such feedback messages may be used in a variety of ways indifferent embodiments at the network health management service. Forexample, in one embodiment the feedback obtained from customers may betreated as another set of metrics, which can then be aggregated togetherwith metrics from other sources to update network health stateinformation for various EPCs or resources. Consider a scenario in whichthe NHMS concludes (and indicates to numerous customers) that trafficbetween a particular availability container AC1 and the public Internetis flowing in an unimpaired manner. If feedback from a large number ofcustomers who are using AC1 contradicts that conclusion, the aggregatedcustomer feedback may potentially be used to trigger more extensiveverification of the state of traffic flow between AC1 and the Internet,and/or to conclude that the state may actually be partially orextensively impaired.

Another way in which feedback message contents may be used by the NHMSin one embodiment is to trigger various types of events or operations ata customer support organization of the provider network. For example,consider a scenario in which, at some time T1, the NHMS concludes thatan impairment event has occurred which is disrupting traffic betweensets of endpoints {E1} and {E2}. The NHMS may notify customers that areexpected to be affected by the event, e.g., using interfaces similar toconsole 1002, APIs, etc. Operations to debug and/or repair theimpairment may be initiated at the provider network. Later, at some time(T1+delta1), based on various metrics and/or on input from the repairingorganization or entities, the NHMS may conclude that the impairment hasbeen fixed, and indicate the completion of repair and the resumption ofunimpaired status to various customers. If a particular customerreceives an indication that the health state of a particular EPC issupposed to be unimpaired, but continues to experience applicationnetworking problems associated with that EPC, a feedback message may betransmitted to the NHMS indicating that the customer's applicationscontinue to be affected negatively. In such a scenario, the NHMS may usethe contents of the contradicting feedback message to, for example, openor escalate a support request, or cause a member of the support staff ofthe provider network to contact the customer from whom the feedback wasreceived. This course of action may be especially appropriate if, out ofa large number of customers whose applications were experiencing anegative impact of the impairment event, most customers report that theyare no longer experiencing the problem, but a particular customer C1continues to experience the problem. In such a situation, somethingspecific to C1's resources or applications may be causing the problem,and as a result a support action for C1 may be initiated.

As mentioned above, a refresh control 1007 may be used to update theinformation being displayed in some embodiments. In other embodiments,instead of or in addition to providing snapshots of health stateinformation, each of which separately indicates network health at agiven point in time, more dynamic views of health information may beprovided. In one such embodiment, a time series of network healthinformation may be represented graphically, with individual networkhealth state records of a given time series representing the state ofone or more resources at discrete points of time over a selected timeinterval. In some embodiments, changes to health state (if and when suchchanges occur) may be represented in the graphical view. For example, inone scenario the health state of a given endpoint pair category may berepresented by a visual “percent unimpaired” indicator. If the endpointpair category is extensively unimpaired as a result of some failure, thepercent unimpaired value may fall to zero or some small integer. Asrepairs are performed, the percent unimpaired value may rise, eventuallyreaching 100%. This change in the degree of impairment may be shown insome embodiments using a graph in which the X-axis represents time andthe Y-axis corresponds to the “percent unimpaired” metric. Having suchdynamic and automatically updated views of health state may beespecially valuable to customers whose applications have been affectedby a failure.

In at least one embodiment, hints regarding the layout of the healthstate information in the graphical view may be provided. For example,information about a logical or physical relationship between aparticular endpoint and another endpoint, or between a particularendpoint category and another endpoint category, which can be used toplace the graphical representations of those entities relative to oneanother may be obtained (e.g., from a source such as a control planecomponent of a virtualized computing service). In one scenario,containment relationships between regions and availability containersmay be provided to the device at which the health state information isgoing to be displayed, together with a directive that region-levelinformation should generally be displayed above availability containerlevel information. Such relationship information and accompanyingdirectives may result in a consistent look-and-feel for the graphicalrepresentations of network health state information—for example,inter-region information may consistently be shown above intra-regioninformation, regardless of the display device or the particular customerto whom the information is displayed. The relationship information maybe included in the data sets generated by the network health managementservice for the graphical displays in some embodiments, or may beobtained separately in other embodiments.

In some cases, customers may wish to drill down to a finer granularityof detail than the summarized level shown in FIG. 10. FIG. 11illustrates an example graphical interface which may be used to providenetwork health state information at the level of individual virtualmachines to a client of a virtualized computing service, according to atleast some embodiments. Starting with a summarized networkrepresentation similar to that of FIG. 10, and using the zoom controls1104 and/or other interface elements of the graphical console 1102, aclient of a VCS may be able to view the state of the network trafficflow between individual resources in the depicted embodiment.

In the zoomed-in network image 1110, the focus is on individualendpoints rather than on endpoint pair categories. Four GVMs are shown:GVM 1110A, 1110B and 1110C in isolated virtual network IVN-K, and GVM1110D in isolated virtual network IVN-L. In at least some embodiments,network health state information at the individual resource level mayonly be shown with regard to pathways over which attempts to transmitnetwork packets have actually occurred, e.g., within a selected timewindow. Thus, for example, in the scenario depicted in FIG. 11, while inprinciple it may be the case that network packets could be transmittedbetween GVM 1110A and GVM 1110D, the health state of that pathway is notindicated because GVMs 1110A and 1110D may not have communicated (orattempted communications) within the previous T minutes relative to thetime for which the information is displayed.

In the example scenario shown, the respective states of network trafficflow between GVM 1110A and five other endpoints are shown: storageobject S01 (which may be managed at a storage service of the providernetwork), GVM 1110B, GVM 1110C, and public Internet endpoints “a.b.c.d”(expressed, for example as Internet Protocol version 4 addresses) and“e.f.g.h”. As indicated by the respective symbols (selected from thesymbol set shown in legend 1106), the health state of most of thetraffic flows associated with GVM 1110A is unimpaired. The exception isthe flow of traffic between S01 and GVM 1110A, which is shown as beingseverely impaired.

Seven traffic endpoints are shown with respect to GVM 1110B: GVM 1110A,GVM 1110C, GVM 1110D, the two public Internet endpoints, and twodatabase instances DB1 and DB2 (which may be managed, for example, by adatabase service of the provider network). The state of the traffic flowfor most of the endpoints with which GVM 1110B is in communication isshown as unimpaired, with the exception of the Internet endpoint“e.f.g.h”, which is shown as partially impaired. With respect to GVMs1110C and 1110D, all the traffic flows for which health information isshown are unimpaired.

It is noted that the level of detail indicated in FIG. 11 may beextremely helpful in narrowing down the root causes of certain types ofunexpected application behaviors. For example, consider the partialimpairment of the network pathway between the GVM 1110B and the Internetendpoint “e.f.g.h”. Since the traffic between GVM 1110A and “e.f.g.h”appears to be unimpaired, this would suggest “e.f.g.h” itself ishealthy, and that the underlying problem causing the partial impairmentmay be associated with the portion of the pathway between GVM 1110B and“e.f.g.h” which is different from the pathway used for packets flowingbetween GVM 1110A and “e.f.g.h”. In various embodiments, additionalcontrols (such as the R-S or repair status buttons shown in FIG. 10, orthe refresh control shown in FIG. 10) may also be included in finergranularity displays such as that shown in FIG. 11. In at least oneembodiment, the network health management service may display separatestate information for traffic in respective directions betweenendpoints—e.g., for some types of metrics such as packet drop rates, thehealth state for traffic flowing from endpoint E1 to endpoint E2 maydiffer from the health state for traffic flowing from endpoint E2 toendpoint E1. It is noted that even at the level of detail shown in FIG.11, virtual representations of physical network links may be provided inat least some cases—e.g., the path between GVM 1110A and 1110B mayactually include multiple physical links and/or multiple physicalnetworking devices, all of which are represented collectively using asingle arrow.

In some embodiments, instead of using zoom controls, clients may beprovided interfaces to name the resources for which they wish to viewhealth state information, as well as the particular sets of healthmetrics to be shown. FIG. 12 illustrates an example graphical interfacewhich may be used to specify health-related metrics to be displayed withrespect to various resources allocated to a client, according to atleast some embodiments. As shown, the web-based console 1202 may includea message area 1203, a region 1204 for indicating request parameters forhealth state information, and a results region 1224 in which responsesto the requests may be shown.

In the depicted embodiment, the client may use button 1206 to add thename of a resource for which network health state information is to bedisplayed. A number of options for the resource type may be provided,e.g., via a drop-down menu in health display request parameter region1204. Example resource types may include GVMs, storage objects, databaseinstances and the like in various embodiments. The identifiers of theresources of the selected types may be supplied by clients in the“Resource ID” column of the health display request parameters region1204. Corresponding to a given resource or resource type, options forthe available health metrics may be provided via drop-down menuassociated with the “Metrics” column in the depicted embodiment. Afterthe client has indicated the specific resources and metrics for whichhealth state information is to be displayed, the “submit request” button1208 may be used to transmit the request to the network healthmanagement service in the depicted embodiment. The request may betranslated into one or more API invocations in some embodiments, with agiven API invocation including elements similar to those shown in FIG.5.

In the health display results region 1224, the metrics requested may bedisplayed for each of the resources indicated in the request. Forexample, as shown, with respect to GVM with identifier “GVM000223”, arequest/response rate to the public Internet of 99.5% in the last 10minutes is indicated. For GVM0007713, for which all available metricswere requested, the request response rate to the Internet, intra-IVNmessage latency and inter-IVM message latency may be shown. For thestorage object with identifier SO5245, the outbound packet drop rate maybe provided as requested. It is noted that in at least one embodiment,clients may be able to specify endpoint pair categories instead of, orin addition to, specific endpoints for which health state information isto be provided using interfaces similar to that shown in FIG. 12. Invarious embodiments, the kinds of information displayed graphically inthe examples of FIG. 10, FIG. 11 and FIG. 12 may also be available in anon-graphical or text-based format from the network health managementservice. Generally speaking, the kinds of information that can beretrieved from the service may be independent of the interface used toretrieve the information in such embodiments—thus, any kind of networkhealth-related information at any permitted granularity and frequencymay be retrieved using any of the supported programmatic interfaces.

Example Tools for Obtaining Network Metrics

As mentioned earlier, a number of different intermediary tools may beused to collect metrics for analysis and aggregation by the networkhealth management service in some embodiments. FIG. 13 illustratesexamples of tools from which data may be collected at a network healthmanagement service, according to at least some embodiments. Additionaldetails regarding some of the tools and associated data sources areprovided below, e.g., in the context of FIG. 14-FIG. 19.

The network health management service 1301 may obtain high-levelconnectivity information, e.g., based on request/response success ratesassociated with pairs of user-mode processes and/or privilegedkernel-mode processes, using a connectivity verifier tool 1310 in thedepicted embodiment. In at least some embodiments, a number of DomainName System (DNS) servers may be utilized at or from a provider network,e.g., for facilitating communications between control-plane componentsof various services as well as for customer applications. One or moreDNS monitor(s) 1330 may keep track of the state of the DNS traffic invarious parts of the provider network—e.g., measuring the latency forresponding to DNS requests, the success rate of DNS requests, and thelike. A DNS failure may have a substantial negative impact on customerapplication communications. As such, the network health managementservice may be able to utilize the output of the DNS monitors 1330 fordetermining the health state of various endpoint pair categories. Asmentioned earlier, in some embodiments one or more of the other servicesaccessed from the VCS, such as a storage service, may allow servicerequests to be transmitted from the public Internet. In some suchembodiments, special endpoints (called virtual private endpoints) may beestablished within the VCS which enable service requests to flow fromthe VCS to the other services (and responses to the service requests tobe received) using provider network resources, without requiring packetsrepresenting the requests/responses to traverse the public Internet.Tools 1335 for monitoring the connectivity to such virtual privateendpoints, and/or performance of traffic flows which utilize the virtualprivate endpoints may also provide metrics to the NHMS in the depictedembodiment.

A number of mechanisms may be made available to clients regarding securenetwork pathways between the virtualized computing service and customerpremise networks (networks external to the provider network, e.g., at anoffice location or a data center owned/managed by the customer). Suchmechanisms may include, for example, dedicated direct-to-customerphysical links and/or virtual private networks (VPNs) in variousembodiments; more details regarding these alternatives are providedbelow in the context of FIG. 16. Respective monitors 1350 and 1340 maybe established for each of these connectivity mechanisms, and utilizedby the network health management service 1301 in at least someembodiments.

In at least one embodiment, a number of monitors 1320 for variousinternal physical links of the provider network may be configured toprovide metrics to the network health management service 1301. Forexample, hardware links connecting rooms within data centers, orconnecting pairs of data centers, may be monitored at a high priority aspart of the infrastructure maintenance functions of the providernetwork. In some embodiments, as discussed below in further detail, anencapsulation protocol may be used to manage network traffic for guestvirtual machines, and monitoring tools 1315 associated with theencapsulation protocol may be configured to provide input to the networkhealth management service. In at least some embodiments, each of thevarious monitors and tools shown in FIG. 13 may run respective sets oftests on their targeted resources or protocols, e.g., at respectiveintervals selected by the tools, and generate metrics in respectivedifferent formats. The network health management service 1301 may beresponsible for collecting and correlating the independently-generatedmetrics, resolving any ambiguities or conflicts, mapping the metrics toendpoint pair categories relevant to different customers, and providingeasy-to-understand customized health state information relevant to theindividual customers. In at least one embodiment, tools similar to thoseshown in FIG. 13 may be implemented as subcomponents of the networkhealth management service itself—for example, connectivity verificationusing request/response tests may be performed by agents of the networkhealth management service.

Connectivity Verifier Tool Implementations

A number of approaches may be used to implement a connectivity verifiertool associated with one or more services of a provider network invarious embodiments. FIG. 14 illustrates examples of guest virtualmachines which may be established as part of a connectivity verifiertool whose output is used by a network health management service,according to at least some embodiments. As shown, availabilitycontainers 1414A-1414D of a virtualized computing service 1410 may eachcomprise numerous customer guest virtual machines (GVMs) 1420 (i.e.,GVMs used for running customer applications). For example, availabilitycontainer 1414A of region 1412A may comprise customer GVMs 1420A and1420B, availability container 1414B of region 1412A may comprisecustomer GVMs 1420D and 1420E, availability container 1414C of region1412B may comprise customer GVMs 1420G and 1420H, and availabilitycontainer 1414D of region 1412B may comprise customer GVMs 1420J and1420K.

In addition to the customer GVMs, one or more connectivity verifier GVMs1425 may be established in each availability container 1414, such asconnectivity verifier GVM 1425A in availability container 1414A, 1425Bin availability container 1414B, 1425C in availability container 1414C,and 1425D in availability container 1414D. In contrast to the customerGVMs 1420 which may be used primarily for running customer applications,each of the connectivity verifier GVMs may be tasked primarily withrunning connectivity tests involving sending messages to (and receivingresponses from) a set of designated endpoints. For example, a list ofnetwork addresses of peer connectivity verification GVMs and/or one ormore external endpoints 1470 may be provided to each connectivityverification GVM 1425 in the depicted embodiment, with an indication of(a) the respective rate at which request messages should be sent to thevarious addresses and (b) properties of the messages (e.g., messagesize, networking protocol, request content, acceptable response content,etc.). In accordance with the addresses and instructions received, forexample, each connectivity verifier GVM may send a respective 200-bytepayload request message to each of 100 destinations per minute, andtrack the number of responses received, the latency of therequest/response round trip, etc. Similarly, when a connectivity requestmessage is received from another GVM, a corresponding response may betransmitted to the requester by a connectivity verifier GVM. Any of avariety of protocols may be used in different embodiments for therequest/response communications, such as variants of HTTP (HyperTextTransfer Protocol), ICMP (Internet Control Message Protocol), and thelike.

In the depicted embodiment, the request/response success rate (e.g., thefraction of requests for which corresponding results were receivedwithin a specified interval) and/or other metrics may be provided byeach connectivity verifier GVM 1425 to a connectivity reporter 1430 inits region 1412 (such as connectivity reporter 1430A in region 1412A andconnectivity reporter 1430B in region 1412B). The network trafficcharacteristics (packet loss rate, latency, etc.) between theconnectivity verifier GVMs may be considered reasonable approximationsof the network traffic characteristics that would be observed by thecustomer GVMs for similar destinations. The connectivity verifier toolmay comprise the reporters 1430 and the special GVMs 1414 in thedepicted embodiment. Network health management service (NHMS) nodes1431, such as NHMS node 1431A and 1431B may collect connectivity metricsfrom the reporters 1430, and generate network health state informationbased at least partly on the connectivity metrics in the depictedembodiment.

In at least one embodiment, an installable agent module for connectivityverification may be made available by the connectivity verifier tooland/or the network health management service. FIG. 15 illustratesexamples of connectivity verifier agents which may be installed atcustomer guest virtual machines and at customer premises for use by anetwork health management service, according to at least someembodiments. In the depicted embodiment, request/response message testsof the kind discussed above may be executed not just by connectivityverifier GVMs 1525 (e.g., 1525A-1525D), but also by the connectivityverifier (CV) agent modules or processes 1527 (e.g., agents 1527A, 1527Band 1527C). Some CV agents may be installed or activated at customerGVMs (such as CV agent 1527A at customer GVM 1520A, CV agent 1527B atcustomer GVM 1520G) within the virtualized computing service, whileother CV agents (such as agent 1527C) may be activated atcustomer-premise hosts 1575.

In various embodiments, the connectivity verifier agents may beconfigurable—e.g., clients may decide various attributes of the testswhich should be run by each agent, the manner in which the resultsshould be provided from the agents (e.g., to connectivity reporters suchas 1530A or 1530B, or directly to NHMS nodes such as 1531A or 1531B).Some clients may wish to install CV agents at selected important subsetsof their resources for which obtaining specific and detailed networkhealth state information is considered a high-priority; other clientsmay install CV agents on all their resources. In at least oneembodiment, the input received from CV agents may be used to detectand/or diagnose network problems at customer premises by the networkhealth management service. As shown, CV agent 1527C may provide metricsto connectivity reporter 1530B, which may be analyzed by NHMS node 1531Bto determine the state of the customer-premises network in which host1575 is configured. It is noted that although region-level aggregationof connectivity verification data is shown in FIG. 14 and FIG. 15, inputfrom the connectivity verifier GVMs and/or agents may be collected atvarious levels of the resource hierarchy in different embodiments. Insome embodiments, CV agents may be utilized, but dedicated connectivityverifier GVMs may not necessarily be instantiated; instead, CV agentsmay be started up as respective processes or threads at customer GVMs.The connectivity verifier GVMs, installable agents, and connectivityreporters shown in FIG. 14 and FIG. 15 may be referred to collectivelyherein as nodes of the connectivity verifier tool. As mentioned earlier,the connectivity verifier tool may be implemented as part of the networkhealth management service in some embodiments.

Secure Network Paths to Customer Premises

FIG. 16 illustrates examples of network pathways to customer datacenters, with respect to which metrics may be obtained by a networkhealth management service, according to at least some embodiments. Asshown, provider network 1602 may comprise an isolated virtual network(IVN) 1605 established on behalf of a particular customer C1. C1 mayalso have computing devices at a number of data centers outside theprovider network, such as device 1645A at data center 1640A and device1645B at data center 1640B in the depicted embodiment. Secure networkconnectivity between the GVMs 1624 (set up on behalf of customer C1 inthe provider network) and the external devices 1645 may be establishedusing virtual private networks (VPNs) and/or dedicateddirect-to-customer physical links in the depicted embodiment.

A direct physical link 1654 may be established at customer C1's requestbetween a customer router 1660 and a provider network router 1662 at arouter co-location facility 1630 or transit center. Such dedicatedphysical links may be referred to as “direct connect” links in someenvironments, and may provide bandwidth that does not have to be sharedby other customers. In one embodiment, for example, a customer may optto configure either a 10 Gbps (Gigabits per second) dedicateddirect-to-customer link or a 1 Gbps dedicated direct-to-customer linkbetween an external data center and the provider network. Any of avariety of protocols may be used for the traffic flowing over thedirect-to-customer links in various embodiments—for example, in thescenario depicted in FIG. 16, a Generic Routing Encapsulation (GRE)protocol tunnel 1652 may be established.

For some customer applications, the dedicated bandwidth associated withdirect-to-customer links may not be required, and a VPN tunnel such astunnel 1656 may be established between a customer gateway and a providernetwork gateway 1610. A variety of different protocols may be used forthe VPN tunnel in different embodiments, such as SSL/TLS (Secure SocketsLayer/Transport Layer Security), DTLS (Datagram Transport LayerSecurity), a combination of IKE (Internet Key Exchange) and IPSec(Internet Protocol Security), and so on. The provider network gateways1610 may be implemented using a variety of approaches in differentembodiments—e.g., using a collection of protocol processing enginesrunning at GVMs, using custom hardware devices, and so on.

In the depicted embodiment, metrics related to the health of thedirect-to-customer links may be collected by monitors 1622A and 1622Band passed on to network health monitoring service nodes such as node1631A for analysis and aggregation with metrics obtained from othersources. Monitors 1622A and/or 1622B may, for example, run a variety oftests over the direct-to-customer link 1654. Similarly, metricspertaining to the virtual private network connection between theprovider network and data center 1640B may be obtained by VPN monitors1624 by running a different set of tests which utilize tunnel 1656, andthe VPN metrics may be passed on for analysis and aggregation to NHMSnode 1631B. In some embodiments, the NHMS nodes may comprise logic toparse and interpret metrics corresponding to the various protocols usedfor connectivity between customer networks and the provider network,such as GRE, IKE, TLS/SSL, IPSec etc. It is noted that some customers ofthe provider network may not utilize direct-to-customer links or VPNs,and part of the responsibility of the NHMS may include determiningwhether VPN-related or direct-to-customer link-related network stateinformation is relevant for a given customer. It is noted that the term“customer data center” may be used synonymously with the terms“customer-owned data center” or “customer-managed data center” herein,and may refer to premise that are managed, owned or run at least in partby entities other than the provider network operator. Similarly, theterm “customer device” may be used to refer to customer-owned orcustomer-managed devices (such as the router 1660).

Packet Tracking at Encapsulation Protocol Layer

FIG. 17 illustrates an example system environment in which datacollected from network packet tracking sessions associated with anencapsulation protocol may be utilized by a network health monitoringservice, according to at least some embodiments. In the depicted system,a number of services including virtual computing service (VCS) 1742,storage service 1752 and database service 1762 are implemented at aprovider network 1702. As discussed earlier, at least some resources ofthe VCS such as virtualization hosts (VHs) 1730A, 1730B and 1730C may bedistributed among one or more isolated virtual networks (IVNs) such asIVNs 1725A and 1725B established at the request of VCS clients.

In the embodiment shown in FIG. 17, IVN 1725A comprises a plurality ofvirtualization hosts 1730, including VH 1730A and VH 1730B, while IVN1725B comprises VH 1730C. Each VH 1730 may include respectivevirtualization management components (VMCs) 1715, such as VMCs 1715A,1715B and 1715C. As discussed earlier, a VMC may comprise, for example,a hypervisor, and/or an instance of an operating system running in anadministrative domain (sometimes referred to as “dom-0”). In someembodiments, or more hardware cards which may perform a subset ofvirtualization management functions, such as network processingperipheral card 1733, may also be considered VMCs. Each VH 1730 may beused to instantiate zero or more GVMs 1712 at a given point in time inthe depicted embodiment. VH 1730A, for example, is shown with three GVMs1712A, 1712B and 1712C; VH 1730B has GVMs 1712K and 1712L, while GVM1712Q is instantiated at VH 1730C. In addition to the virtualizationhosts 1730, a VCS 1742 may also contain various other componentsincluding edge routers 1728 and nodes 1726 (e.g., 1726A and 1726B) of anetwork health management service 1758 in the depicted embodiment. It isnoted that in some embodiments, at least some NHMS nodes 1726 may be setup outside the VCS 1742.

In order to facilitate traffic between GVMs 1712 instantiated atdifferent virtualization hosts 1730 (and between the GVMs 1712 andentities outside the VCS 1742, such as various network endpoints ofservices 1751 or 1752, as well as endpoints outside the provider network1702), an encapsulation protocol may be implemented at various devicesof the VCS 1742. Software and/or hardware components responsible forimplementing the encapsulation protocol, labeled encapsulation protocolprocessing components (EPPCs) 1717, are shown incorporated within VMCs1715 (including within network processing peripheral device 1733), andwithin edge router 128 in system 100. For example, VMC 1715A of VH 1730Aincludes EPPC 1717A, VMC 1715B includes EPPC 1717B, network processingperipheral device 1733 includes EPPC 1717C, and edge router 1728includes EPPC 1717K. A virtualization host such as VH 1730C may beequipped with a network processing peripheral device 1733 in someembodiments so that, for example, some of the computing workloadassociated with implementing one or more network protocols (such as theencapsulation protocol itself and/or the underlying Transmission ControlProtocol (TCP), User Datagram Protocol (UDP) or Internet Protocol (IP))can be offloaded from the main CPUs or cores of the virtualization host.In some embodiments, the network processing peripheral device may beattached via the Peripheral Component Interconnect Express (PCI-Express)bus or another similar bus. In one embodiment, a customized or enhancednetwork interface card may serve as the network processing peripheraldevice for some virtualization hosts. In embodiments in which networkprocessing peripheral devices are used at one or more virtualizationhosts, some of the networking-related responsibilities of the hypervisorand/or administrative domain operating system which constitute the VMCsof the hosts may be delegated or offloaded to the peripheral devices,and as a result more of the processing capabilities of the CPUs/cores ofthe hosts may become available for guest virtual machines.

According to the encapsulation protocol, a message generated at anapplication process executing at a particular GVM (e.g., GVM 1712C) of aparticular virtualization host (e.g., VH 1730A) and directed to anapplication process at a different GVM (e.g., GVM 1712L) at a differentvirtualization host (e.g., VH 1730B) may be included in an outboundbaseline packet OBP1 at the networking software stack of the source GVM1712C. The dashed arrow labeled 1766B indicates that customer data(i.e., messages generated at the application level) is being transmittedbetween GVM 1712C and GVM 1712L in the example scenario illustrated inFIG. 17. The term “baseline” is used herein to refer to the packetsgenerated at or received by the networking software stacks of variousGVMs, as opposed to the typically larger “encapsulation” packetsdescribed below, which are generated by the EPPCs 1717. (In some cases,of course, a message may be large enough to require multiple baselinepackets, in which case each of the multiple baseline packets may beencapsulated similarly.) Assuming that an IP-based networking protocolis used for GVM-to-GVM communication, the outbound baseline packet OBP1may indicate an IP address GVMAddr1 assigned to GVM 1712C as the sourceIP address, and an IP address GVMAddr2 assigned to GVM 1712L as thedestination address. In various embodiments, the IP address assigned toa GVM (or, more specifically, to a virtual network interface associatedwith the GVM) may typically differ from the IP address assigned to thevirtualization host at which that GVM runs. For example, VH 1730A mayhave an address VHAddr1 assigned to it, and VH 1730B may have addressVHAddr2 assigned to it. In order to route GVM-to-GVM packets correctly,network mappings indicating the relationship between GVMs andvirtualization hosts, as well as route tables set up for the IVNs 1725may be used, e.g., as part of the encapsulation protocol.

In the example where the outbound baseline packet OBP1 is created at GVM1712C of VH 1730A, the virtualization management component VMC 1715A ofVH 1730A may intercept OBP1, and a corresponding outbound encapsulationpacket OEP1 may be prepared by EPPC 1717A. OEP1 may include one or moreheaders defined by the encapsulation protocol, for example, and the bodyof OEP1 may include OBP1. In at least some embodiments, OEP1 mayindicate host address VHAddr1 as a source address, and VHAddr2 (or someintermediary address on a route towards VH2) as a destination address.OEP1 may be transmitted using VH 1730A's physical network interface card(NIC) on its path towards VH 1730B. When OEP1 reaches VH 1730B, EPPC1717B of the VMC 1715B may examine its contents, and the baseline packetcontained in OEP1 may be provided to GVM 1712L. A similar encapsulationtechnique may be employed for inbound packets with respect to a givenGVM 1712 (e.g., a baseline packet generated at GVM 1712L may beincorporated within an encapsulation packet generated by EPPC 1717B ofVMC 1715B, received and validated at EPPC 1717A of VMC 1715A, extractedand passed on to GVM 1712C).

In the scenario depicted in FIG. 17, customer data traffic (e.g.,encapsulation packets containing baseline packets generated at GVMs1712, or directed to GVMs 1712) flows between GVMs 1712C and 1712L, GVMs1712K and 1712Q, and GVM 1712B and service storage service 1751 via edgerouter 1728, as indicated by arrows 1766B, 1766C and 1766A respectively.In general, customer traffic may flow between any two GVMs, or betweenany given GVM and devices external to the VCS 1742. Corresponding to atleast some pairs of such communicating endpoints, respective packettracking sessions 1767 may be established between the EPPCs involved.For example, packet tracking session 1767A has been established betweenEPPC 1717A of VH 1730A and EPPC 1717K of edge router 1728, and packettracking session 1767B has been established between EPPC 1717B of VH1730B and EPPC 1717C of VH 1730C. Each session 1767 may be establishedat the request of one of the EPPCs of the pair of EPPCs participating inthe session. The EPPC requesting the session may be referred to as the“transmitter” or “TX” EPPC of the session, while the EPPC accepting thesession establishment request may be referred to as the “receiver” or“RX” EPPC of the session.

Any of a number of criteria may be used to determine if and when a givenEPPC should attempt to establish (as the TX EPPC) a packet trackingsession, and the particular peer EPPC which should be selected as thepotential RX EPPC of the session. For example, each EPPC may have afixed-size pool of tracking resources (e.g., units of memory) in someembodiments, such that a selected subset of resources of the pool has tobe reserved for any given session. An EPPC may attempt to establish anew packet tracking session, for example, if a tracking resource of thepool has recently been freed as result of a termination of anotherpacket tracking session, or based on other criteria such as thereception of a network health state request at the NHMS. The peer EPPCwhich is to assume the role of RX EPPC may also be selected based on anycombination of several criteria, such as the length of a time intervalduring which at least some encapsulation packets have been transmittedper minute or second between the TX EPPC and the proposed RX EPPC, thenumber of encapsulation packets which have been transmitted between thetwo EPPCs, the number of bytes which have been transmitted between thetwo EPPCs during a particular time interval, or the length of a timeinterval elapsed since a previous session between the two EPPCs ended.Not all communicating EPPC pairs may have corresponding trackingsessions established at a given point in time; for example, no sessionis shown for the EPPC pair (EPPCs 1717A and 1717B) corresponding tocustomer data path 1766B. Depending on the communication needs of theapplications which are being run at the virtualization hosts of the VCS,and the constraints on tracking resources available at the EPPCs, it maysometimes be the case that packet tracking sessions can be set up foronly a fraction of the communicating EPPC pairs of the VCS at a givenpoint in time. For example, a given EPPC may be transmittingencapsulation packets to hundreds of destinations, but may be limited toparticipating in eight or sixteen tracking sessions at a time.

The session-initiating or TX EPPC may transmit an encapsulation packetto the proposed RX EPPC as part of a handshake procedure in the depictedembodiment, using one or more encapsulation headers or encoded bitsequences to request the participation of the RX EPPC in the session.After the session is established, the TX EPPC may tag some or all of theencapsulation packets (which contain embedded baseline packets) aspackets to be tracked. A number of metrics may be maintained regardingthe tracked packets at the RX EPPC and/or at the TX EPPC, such as thetotal number of packets sent, the total amount of data sent, the numberof dropped or corrupted packets received, the number of out-of-orderpackets received, the latency associated with a particular route usedfor the packets relative to other routes, etc. Periodically, or inresponse to triggering conditions, the TX EPPC of a session 1767 mayrequest that the metrics collected thus far at the RX EPPC betransmitted back to the TX EPPC. The TX EPPC may send the networkmetrics obtained from the RX EPPC to one or more of the nodes 1726 ofthe NHMS 1758 in the depicted embodiment. The scheduling of the networkhealth update messages may be based on various parameters in differentembodiments: e.g., one update message may be sent per set of metricsreceived from the RX EPPC, or update messages may be sent based on apreliminary analysis of the metrics obtained from the RX EPPC, or updatemessages may be sent in response to requests from the NHMS 1758. Thecontents of the update messages sent by a given EPPC 1717 may beanalyzed at the NHMS 1758 to generate network health state informationfor various endpoint pair categories (or for specific pairs ofendpoints) as discussed earlier.

In various embodiments, some or all of the messages exchanged betweenEPPCs to set up, terminate, or change the parameters of network packettracking sessions and/or for reporting of collected metrics maythemselves be contained in encapsulation protocol headers. In someembodiments, encapsulation packets used for such administrativeoperations may not necessarily contain baseline packets generated by orfor the GVMS 1712. Thus, some session management messages may bepiggybacked onto encapsulation packets which also carry customer data(baseline packets), while other session management messages may notcontain baseline packets. The tracked packets (the ones for whichmetrics such as corrupted packet counts or dropped packet counts arecollected) may typically contain baseline packets containing customerdata. At least some communications between the EPPCs and the NHMS mayalso be implemented using packets formatted according to theencapsulation protocol in various embodiments. By tracking encapsulationpackets used for customer data, a more representative measure of theperformance being experienced by client applications of the VCS may beobtained than may have been possible if health monitoring agents thatuse heartbeat messages or pings were the only source of network healthinformation.

FIG. 18 provides an overview of network packet flow using encapsulationbetween virtual machines instantiated at different virtualization hosts,according to at least some embodiments. Two virtualization hosts VH1830A and VH 1830B of a virtual computing service (VCS) are shown. Bothof the VHs 1830 may be used for GVMs of the same isolated virtualnetwork (IVN) in the depicted example, although similar packet flowpaths may be used even if the two VHs are used at different IVNs, or ifIVNs are not used at all. Each virtualization host may comprise one ormore guest virtual machines, such as GVMs 1812A and 1812B at VH 1830A,and GVMs 1812K and 1812L at VH 1830B. In the depicted embodiment, eachGVM 1812 may be assigned at least one private IP address (such as PA-A,PA-B, PA-K or PA-L for GVMs 1812A, 1812B, 1812K and 1812L respectively),e.g., from the range of addresses of a subnet previously set up by thecustomer on whose behalf the IVN containing the GVM is established. Forexample, if the IP address range (expressed in Classless Inter-DomainRouting or CIDR format) 10.0.0.0/16 is designated for the IVN, and GVMs1812A and 1812B are set up in a subnet 10.0.1.0/24, then GVM 1812A and1812B may each be assigned a different address in the range10.0.1.0-10.0.1.255. The addresses may be designated as “private” in thedepicted embodiment because they are not (at least by default)advertised outside the IVN. It is noted that at least in someembodiments, a private IP address (as the term is used in this document)may not necessarily be compliant with some or all of the IETF (InternetEngineering Task Force) standards pertaining to address allocation forprivate networks, such as RFC (Requests for Comments) 1918 (for IPversion 4) or RFC 4193 (for IP version 6).

Each GVM 1812 may comprise one or more application processes 1811 in thedepicted embodiment, such as applications 1811A, 1811B, 1811K or 1811L.A given application such as 1811A may generate messages to be sent toother applications, such as 1811L. Such an application message may beincorporated within one or more baseline network packets (such as packet1844A, in the case of application 1811A) prepared by the networkingsoftware stack of the operating system at the GVM where the applicationruns. The baseline packet may, for example, indicate the private addressof the sending GVM (e.g., PA-A) as the source IP address, and theprivate address of the intended recipient GVM (e.g., PA-L) as thedestination IP address. The baseline packet may be transmitted by thelow level components of the GVM's networking software stack via avirtual network interface associated with the GVM. The VMC 1815 at thevirtualization host where the GVM runs (e.g., VMC 1815A, which maycomprise a hypervisor and/or an administrative domain operating system),which acts as the intermediary between the GVM and hardware components1825A, may intercept such a baseline packet 1844A. The EPPC 1829A of VMC1815A may include the contents of the baseline packet within anencapsulation packet 1845A. As discussed earlier, an encapsulationprotocol may be employed in the VCS because the addresses of the GVMsmay have to be mapped to the addresses of the virtualization hosts atwhich the GVMs are instantiated for the transmission of the packetsalong the routes needed to reach their destinations. For example, VH1830A has a network interface card with host IP address HA-A, and VH1830B has a network interface card with host IP address HA-B, while therespective GVMs established at the hosts 1830 have different IPaddresses from the range selected by the customer. The VMC 1815A maydetermine the route over which the encapsulation packet 1845A should besent using route tables of the IVN, network mappings and/or other VCSnetworking configuration metadata (which may compriseidentifiers/addresses of gateways and other devices, etc.). Theencapsulation packet 1845A may indicate VH 1830A's host IP address HA-Aas the source, and the targeted VH 1830B's host IP address HA-B as thedestination (although in some cases the destination address indicated inthe encapsulation packet may be an address assigned to an intermediarydevice at which the address of VH 1830B may be available). Theencapsulation packet 1845A may be transmitted along the appropriateroute towards VH 230B, e.g., a route which may include variousintermediary devices 1885 such as routers, tunneling devices, etc.

The encapsulation packet 1845A may eventually be received at the networkinterface card (one of the hardware components 1825B) of virtualizationhost 1830B. The encapsulation packet 1845A may be processed by the EPPC1829B of VMC 1815B. EPPC 1829B may unpack the contents of theencapsulation packet 1845A. The original baseline packet 1844A extractedfrom encapsulation packet 1845A may be passed on to the GVM 1812L atwhich the destination application 1811L runs. Packets generated at theapplication 1811L and intended for application 1811A may follow thereverse path to that used for baseline packet 1844A. For example, abaseline packet 1844B (generated at GVM 1812L) with a source IP addressPA-L and destination IP address PA-A may be intercepted and encapsulatedby EPPC 1829B, and a corresponding encapsulation packet 1845B may beprepared and transmitted using intermediary devices 1885. Thatencapsulation packet 1845B, with a HA-B as its source address and HA-A(or an intermediary device address) as its destination address, mayeventually reach VH 1830A. At VH 1830A, EPPC 1829A of VMC 1815A mayextract baseline packet 1844B from encapsulation packet 1845B andtransfer it to GVM 1812A. A number of different encapsulation protocolheader values or bit sequences may be set by the EPPCs 1829 forestablishing packet tracking sessions, tracking packets during thesessions, obtaining metrics at a TX EPPC of a session from the RX EPPCfor the session, and so on. As mentioned earlier, in some embodiments atleast a portion of the EPPC functionality discussed in the context ofFIG. 18 may be implemented or executed at peripheral networkingprocessing devices of the virtualization hosts, e.g., instead of beingimplemented within a hypervisor or administrative domain operatingsystem.

FIG. 19 illustrates example metrics which may be obtained with respectto a network packet tracking session, according to at least someembodiments. The TX EPPC 1902 of the session may transmit a trackingsynchronization request message 1922 which includes a session ID 1934(indicating the session for which metrics collected at the RX EPPC arebeing requested), and a synchronization identifier 1932 which is used tomatch tracking synchronization requests with their respective responses.Such tracking synchronization request messages may be sent one or moretimes during a packet tracking session. The TX EPPC may determine whento send a tracking synchronization message 1922 based on variouscriteria in different embodiments—e.g., at regular time intervals suchas once every T seconds, after a particular number of packets or numberof bytes have been sent to the RX EPPC since the previous trackingsynchronization message was sent, in response to a request received fromthe network health management service to report tracking results, etc.

In response to receiving the tracking synchronization request message1922, the RX EPPC 1912 may first verify that the session ID 1934 in themessage corresponds to a session for which the RX EPPC has beencollecting metrics. If the session ID does not match a tracked session,a tracking error message may be sent to the TX EPPC. If the session IDis validated, the RX EPPC may prepare a tracking synchronization resultsmessage 1976 and transmit it to the TX EPPC 1902 in the depictedembodiment. The results message 1976 may include the synchronizationidentifier 1932 (corresponding to the request message 1922'ssynchronization identifier) and session-level network metrics 1965 inthe depicted embodiment. In some embodiments, UDP (the User DatagramProtocol) may be used for transmitting packets between VHs, andrespective sets of metrics may be collected for different UDP sourceports (and corresponding alternate pathways between the TX EPPC and theRX EPPC). In such embodiments, an array of metric sets with one arrayelement for each of the different UDP source ports used during thesession may be included in the results message 1976. Any combination ofa number of different types of network metrics may be collected for eachport (and/or for the session as a whole) in different embodiments. Forexample, per-port metrics 1967A for a given port 1951A may include thetotal number of packets received 1952A, the number of ECNs (explicitcongestion notifications) received 1954A, the number of out-of-orderpackets received 1956A, the number of corrupted packets received 1958A,and one or more latency measures such as the latest latency recorded fortransmitting encapsulation packets using that port. In some embodiments,estimates of the packet transmission latency may be obtained by the RXEPPC as follows: when a hash change notification message is received,indicating that the next encapsulation packet sent by the TX EPPC willuse a different port (and hence a different path), the RX EPPC may starta timer. When the next encapsulation packet is received, the timer maybe stopped, and the elapsed time indicated by the timer may beconsidered a measure of the latency for the new path (e.g., under theassumption that the TX EPPC sent the encapsulation packet immediatelyafter sending the hash change notification message).

Additional metrics, such as one or more route traces available at the RXEPPC, which identify the intermediary routers and links used for thealternate paths between the RX EPPC and the TX EPPC may also be includedin the tracking synchronization results messages in some embodiments.Some of the network metrics shown in FIG. 19 may not be collected orprovided to the TX EPPC in some embodiments. In embodiments in whichper-port metrics are not collected, a single set of metrics may beprovided to the TX EPPC for the session as a whole instead of an arraywhich includes one entry per port. In at least some embodiments,identifiers or private IP addresses of the source and destination GVMsmay be extracted from the baseline packets, and such identifiers may beincluded in the collected metrics so that analysis can be performed onthe per-GVM level instead of or in addition to at the EPPC level.Detailed metrics of the kind shown in FIG. 19 may enablefine-granularity health state information to be generated at the networkhealth management service. Such information may be used to filterreports of network health impairment in some embodiments, as discussedbelow in further detail. It is noted that different approaches towardsmeasuring network performance and health state at the encapsulationprotocol layer may be used in some embodiments—e.g., pairs of EPPCs mayperiodically send messages which do not contain customer data to oneanother.

Filtering Network Health Information Based on Customer Impact

FIG. 20 illustrates an example system environment in which, prior topresentation via a programmatic interface, network health stateinformation may be filtered based on anticipated customer impact ofimpairment events, according to at least some embodiments. In system2000, the resources of a virtualized computing service 2010 may bedistributed among several availability containers, includingavailability container 2014A. Data center 2016A of availabilitycontainer 2014A comprises resources which are used on behalf of numerouscustomers, including customers C1, C2 and C3. The respective sets ofresources used by different customers may overlap at least partiallywith one another. For example, as shown, the intersections of resourcesets 2075A (used by customer C1), 2075B (used by customer C2) and 2075C(used by customer C3) are non-null. The resources 2075 may include, forexample, virtualization hosts at which virtual machines of the customersare instantiated, network links, devices such as routers, gateways andthe like, and so on. Some of the resources (such as the network linksand networking-specific devices) may be non-public—that is, informationabout some resources may not be accessible to customers directly, atleast by default.

Despite the use of a variety of tools and data sources of the kindsdiscussed earlier, the number of distinct resources and network pathwaysbetween resources in a large provider network may sometimes be too largeto permit health state information for all possible endpoints to becaptured and maintained on an ongoing basis. For example, the VCS 2010(and/or other network-accessible services of the provider network) maycomprise hundreds of thousands of hosts, individual ones of which may beused to instantiate dozens of guest virtual machines, and large numbersof networking devices may be established to support communications amongthe GVMs and between GVMs and resources of the other services. In atleast some scenarios, therefore, the metrics available to a networkhealth management service (NHMS) may not always be complete enough tomake an immediate determination as to whether a given network healthimpairment event (such as a hardware or software failure at a particularrouter or switch) is going to impact the applications being run onbehalf of a given customer.

In the depicted embodiment, an NHMS node 2020 may detect the occurrenceof a network health impairment event 2050 using some of the metrics ithas collected from various data sources and tools such as theconnectivity verifier, DNS monitors, VPN monitors and the like. Theexample network health impairment event 2050 shown in FIG. 20 may belocalized, in the sense that it affects only a subset of resources ofdata center 2016A and therefore only a subset of resources ofavailability container 2014A. However, determining whether anyparticular application would be affected by the event 2050, even if theapplication utilizes resources of data center 2016A, may not bestraightforward. According to at least one embodiment, the NHMS mayestimate or compute probabilities as to whether the event 2050 is goingto impact an application based on a number of factors. For example,encapsulation protocol layer metrics 2022 collected using packettracking sessions between encapsulation protocol processing components(EPPCs) such as those discussed in the context of FIG. 17-FIG. 19,metadata 2024 indicating the particular services and features being usedby various customers, and/or resource network configuration and locationmetadata 2026 may be used to determine the probability of applicationimpact in the depicted embodiment. The network configuration settingsinformation, may, for example, indicate IP addresses, subnets, isolatedvirtual network identifiers and the like, which in turn may be mapped tophysical locations within the data center. The encapsulation protocollayer information may provide metrics pertaining to packet loss, latencyand the like for the virtual machines resident at specificvirtualization hosts, and may hence be usable to identify the particularcustomers whose applications run on the virtualization hosts. Serviceusage information may make it easier to determine whether a givenimpairment event is going to affect a customer—for example, if theimpairment event is a failure of a router used for traffic between theVCS and a storage service SS1, and customer C1 is not using SS1, thenthe probability of the failure affecting C1 may be estimated to be low.

Depending on the estimated probabilities of impact, information aboutthe impairment event 2050 may be filtered prior to presentation tocustomers. The filtering algorithm 2030 may, for example, determine thatthe probability that event 2050 would impact customer C1 is below athreshold, and the NHMS node 2020 may therefore transmit state message2014A to C1 indicating that one or more endpoint pair categoriesrelevant to C1 are unimpaired (as indicated by the symbol 2060A).Similarly, if the probability that applications of customer C2 areaffected be event 2050 is below the threshold, state information 2014Bindicating that C2′s endpoint pair categories are unimpaired may beprovided to C2. In contrast, in the depicted scenario, the probabilityof a negative impact to C3's application may be estimated to be above athreshold. Consequently, the state information 2014C may indicate animpaired state of one or more endpoint pair categories relevant to C3(as indicated by symbol 2061). In the depicted embodiment, in additionto the state information itself, a notification 2017 of the impairmentevent may be provided to customer C3. In some embodiments, an interfacewhich can be used by customer C3 to request repair status correspondingto the impairment event may also be provided (e.g., analogous to the R-Sbuttons shown in FIG. 10).

In some embodiments, a notification of the impairment event may beprovided as part of network health state even to those customers who maynot be affected by the event—e.g., customer C1 may be notified thatevent 2050 has occurred, but that C1's applications remain unaffected.Such notifications may be helpful, for example, in reducing customeruncertainty regarding impairment events. For example, if customer C1learns (e.g., from social media or other sources) that a failure eventhas occurred at the provider network, but is unsure as to whether theevent affects C1's applications, a message affirming that C1'sapplications are expected to be unaffected may be helpful. In variousembodiments, the state information 2014 may be provided in response tohealth state requests or queries. In some embodiments, the health stateinformation 2014 may be pushed to customer devices even if no specifichealth state request has been received. Graphical representations of thecustomer's networked resources, and the health state of various endpointpair categories and/or individual endpoint pairs may be provided in atleast some embodiments. In different embodiments, combinations of one ormore of the techniques and algorithms described in the context of FIG.1-FIG. 19 may be employed to facilitate the type of informationfiltering illustrated in FIG. 20. For example, the NHMS may verify,using a plurality of independent data sources, that the impairment event2050 has occurred, before providing an indication of the event to acustomer. Information obtained from a variety of data sources may haveto be parsed and correlated before a determination of health statecorresponding to a given endpoint pair category is made, and so on.

Methods for Network Health State Determination and Reporting

FIG. 21 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service, according to at leastsome embodiments. As shown in element 2101, a set of data sources fromwhich network metrics are to be collected to derive network health stateinformation pertinent to various customers or clients of a providernetwork may be identified. In some cases, intermediary tools may be usedto obtain the metrics, while in other cases the metrics may be obtaineddirectly from the underlying data sources such as user-modeapplications, operating systems, virtualization management componentsand the like. A wide variety of intermediate tools may be employed indifferent embodiments, including for example a connectivity verifiertool with a fleet of nodes which perform request/response tests, orvarious infrastructure monitors which can access metrics pertaining tonon-public resources which are not visible to or accessible tocustomers. The infrastructure monitors may, for example, execute testswhich monitor selected hardware links between various parts of theprovider network, tests involving DNS queries, VPN traffic flow, trafficacross dedicated direct-to-customer physical links of the kind discussedabove, and so on. In some embodiments, packet tracking sessions may beestablished at an encapsulation protocol layer to obtain metricsassociated with packets flowing to/from customer guest virtual machines,and the metrics obtained using such sessions may be examined at thenetwork health management service.

Control-plane metadata from the services of the provider network may beobtained to determine the particular endpoint pair categories for whichnetwork health state information may be relevant to various customers(element 2104). For example, in one embodiment, an account identifier ofa particular customer may be determined, and the set of isolated virtualnetworks (IVNs) established for the account identifier may be obtainedfrom a virtualized computing service control-plane component. The listof other services which are being used by the customer from each of theIVNs may be determined, e.g., either based on records of traffic flowacross IVN boundaries or from service subscription or billing metadata.Some customers may have thousands of individual guest virtual machinesand use a large number of different services, so providing health stateat the individual endpoint level may not be practicable or useful. Basedon the examination of the metadata and/or traffic flow information, aset of endpoint pair categories which are easy to understand and/orvisualize may be derived, so that network health information can beprovided on a summarized basis to respective customers. Consider ascenario in which a control-plane component of the virtualized computingservice indicates that a particular customer C1 has 100 and 150 guestvirtual machines respectively in each of two IVNs (IVN1 and IVN2), andthat half of the GVMs in each IVN are part of availability containerAC1, while the other half are in a different availability container AC2.Furthermore, the control-plane component also provides metadataindicating that a gateway to access the public Internet has been set upfor each IVN, IVN1 and IVN2. Given this information, the NHMS may beable to derive a small set of endpoint pair categories (e.g.,corresponding to combinations with one endpoint in each of the four{IVN, AC} combinations and one endpoint representing the publicInternet, etc.), which may be used to provide easily understandablesummary network health state information to C1. In at least someembodiments, the metadata collected from service control planecomponents may include physical location information regarding resourcesallocated to or used by customers, in addition to logical containmentinformation (such as which GVMs of the customer belong to which IVN).The physical location information may be especially useful in matchingmetrics reported by infrastructure monitors to the endpoint paircategories of the customers. In various embodiments, the endpoint paircategories may be used to generate a virtual view of the networkresources being used for a customer. The paths between the endpoints ofa category may comprises a virtual representation of one or morephysical network links and/or devices, for example.

Respective networking-related metrics sets may be collected, e.g.,periodically, from the data sources and/or intermediary tools at thenetwork health managing service (element 2107). In at least someembodiments, metrics sets corresponding to different data sources may beformatted differently and/or may be collected at different rates. Themetrics sets may also refer to the same underlying entities usingdifferent names or different units in some cases, which may requiredisambiguation and/or normalization by the network health managementservice.

In at least some embodiments, respective weights or trust scores may beassigned to the different metrics sets or tools (element 2110). Theweights may be assigned based on a variety of factors in differentembodiments, including for example a physical location of a resource towhich the metric set or tool corresponds, a layer of a networking stackto which the metric set or tool corresponds, or a collection times ofthe metrics. In one embodiment, a knowledge base entry accessible to thenetwork health management service may indicate how reliable a given toolhas been with regard to providing information about network failures orother impairments, for frequently the tool has led to the presentationof false positive reports of network impairment events, and so on. Thecontents of such knowledge base entries (which may be updated as moreevidence becomes available over time) may be used to assign weights insuch embodiments.

Using the weights assigned to the collected metrics, network healthstate may be determined with respect to endpoint pair categories ofrelevance to a given customer (element 2113). In one embodiment, forexample, network pathways between the resources corresponding to eachendpoint of an endpoint pair category may be identified, and a subset ofthe metrics which correspond specifically to the physical and/or logicaldevices and links forming those pathways may be extracted and analyzedto determine the network health state for that endpoint pair category.As the metrics may be collected at high volumes from large numbers ofsources and tools, various techniques to enable efficient indexing andquerying of large dynamic data sets (e.g., using in-memory data modelsor non-relational data models) may be employed in such an embodiment. Insome implementations, the collected metrics may be organized and storedin such a way that the efficient elimination of irrelevant metrics isfacilitated. For example, metrics may be partitioned or indexed byservice in one implementation, so that if a customer's service usagemetadata indicates that service S-k is not used by the customer, thenall the metrics pertaining to S-k may quickly be designated asirrelevant with respect to the health state of endpoint pair categoriesof that customer. In some embodiments, the state may be expressed inimpairment-related summary form for each endpoint pair category—e.g.,the network health of a given endpoint pair category may be deemed to be“unimpaired”, “partially impaired”, or “extensively impaired”. Insteadof these particular state summaries, other alternatives for expressingsummarized health states indicating respective degrees of impairment maybe used in some embodiments. The determination of the summarized statefrom the weighted network metrics may involve the use of one or morerule-based algorithms in some embodiments. Rules such as the logicalequivalent of “if (metric set MS1 from tool T1 indicates impairment ofendpoint pair category EPC1 with a probability p1>PA, and p1<PB) and(metric set MS2 from tool T2 indicates impairment of endpoint paircategory EPC1 with a probability p2>PC and p2<PD), then the summarystate for EPC1 is partially impaired” may be employed in someembodiments. In one implementation, a machine learning algorithm (e.g.,a regression algorithm) may be used to determine the summary healthstate for the various endpoint pair categories. The use of the machinelearning algorithm may have the benefit that, as more evidenceindicating the accuracy of the conclusions reached at the network healthmanagement service is accumulated, the model(s) used may be enhanced,leading to increases in accuracy. The information regarding the healthstate of the various endpoint pair categories associated with a givencustomer may be transmitted to one or more destinations (e.g., to aclient-side program or console) in the depicted embodiment (element2116). In at least one embodiment, instead of or in addition totransmitting the information to the one or more destinations, the healthstate information may be stored in a persistent repository, e.g., forlater analysis.

FIG. 22 is a flow diagram illustrating aspects of an algorithm foraggregating and verifying network health information, according to atleast some embodiments. As shown in element 2201, respective sets ofmetrics {MS1, MS2, MS3, . . . } may be obtained from various metricscollectors {MC1, MC2, MC3, . . . } in the depicted embodiment. In someimplementations, some or all of the metric sets may comprise timeseries, with new metrics being collected or reported at selected timeintervals. The metric sets may be provided in different formats ornotations in different embodiments—e.g., a given metrics collector mayuse any plain text format, JSON, XML, and/or binary encodings such asBSON (Binary JSON), and so on. Furthermore, even if two tools or metricscollectors use the same format (such as XML), the underlying data model(such as the Document Type Definition or DTD) used may differ from onetool to another. Accordingly, the network health management service mayparse the metrics sets received from the different sources and convertthem into a standard or normalized format (element 2204).

In at least one embodiment, the metrics may be grouped into temporalbuckets (element 2207), e.g., because the rates at which they arereceived from the different collectors may vary. For example, aconnectivity verifier tool may provide reports once every minute, whilean infrastructure monitor for a hardware link may report its metricsonce every five seconds, and the network health monitoring service mayhave to assign each set of metrics to a selected interval (e.g., atwo-minute interval). Different metric sets may refer to the sameunderlying entities or quantities using their respective naming schemes,and the network health management service may have to correlate metricsfrom different sources (element 2210), e.g., using a dictionary ordatabase that maps names used by one tool to names used by another. Forexample, one tool may refer to a given virtualization host by an IPaddress “a.b.c.d”, while another tool may refer to the virtualizationhost by an application label (such as “WebServer1”) or a locationindicator (e.g., “H04.Rk003.Ro007.DS1” indicating the fourth host inrack 3 in room 7 of data center DS1), and metrics referring to anyparticular one of those names may be correlated with metrics referringto other names. In some embodiments, the particular resource or entityto which a given metric set applies may not necessarily be immediatelyevident—e.g., it may be the case that a given host has two NICs withrespective IP addresses “a.b.c.d” and “a.b.c.m”, and network trafficstatistics for the two addresses may be reported separately. In suchscenarios, the network health management service may have to examine aconfiguration database to disambiguate the data—i.e., to determine thatboth sets of metrics refer to the same host.

As mentioned earlier, a set of endpoint pair categories for which healthstate information is to be provided to a customer may have beendetermined, e.g., based on the set of services used by the customer, theset of resources allocated to the customer, etc. At least some of themetrics pertaining to a given endpoint pair category may be collectedfrom a physical network device used for the traffic associated with thecategory in some embodiments. A preliminary health state with anassociated confidence level may be determined for a given endpoint paircategory, e.g., using weights assigned to the respective metricscollectors and the reported metrics as discussed above (element 2213).If, for example, there are four metrics sets from four different metricscollectors, all of which appear to indicate a network failure affectingan endpoint pair category, a high confidence level (e.g., 90%) may beassigned to the “substantially impaired” health state for the category.If, in contrast, one of the four metrics collectors indicates animpairment, one indicates no impairment, and the remaining two do notprovide any clear-cut conclusions regarding the impairment, a lowerconfidence level (e.g., 20%) may be assigned to the “substantiallyimpaired” health state for the category and a medium confidence level(e.g., 40%) may be assigned to the “partially impaired” and “unimpaired”states.

If the confidence level associated with one of the health states exceedsa threshold (where the threshold itself may be a parameter which istuned or adjusted over time), as detected in operations corresponding toelement 2216, the health state for the endpoint pair category for thecurrent iteration of analysis may be deemed to be reportable (element2228). If, however, none of the health states has a confidence levelwhich exceeds the threshold (as also determined in operationscorresponding to element 2216), the network health management servicemay determine whether additional confirmatory sources of metrics areavailable for the endpoint pair category being considered. If one ormore such sources (which may for example comprise additional metricscollectors whose input was not included in the preliminary determinationof the health state) are available (as detected in element 2219), newmetrics may be obtained from the additional sources (element 2222).Based on an analysis of the new metrics in combination with thepreviously-examined metrics, the health state and/or the confidencelevels for the endpoint pair category may be re-computed or adjusted.The confidence level may be checked again to determine whether it isabove the threshold, and the operations corresponding to elements 2216,2219 and 2222 may be iterated until either a confidence level thatexceeds the threshold is obtained, or all the sources of additionalinformation are exhausted. If data sources are exhausted and thethreshold confidence level has still not been reached, the endpoint paircategory may be designated as unclear or unreportable in the depictedembodiment (element 2225).

If more endpoint pair categories remain to be analyzed (as detected inelement 2231), operations corresponding to elements 2213-2225 may beperformed for the next endpoint pair category. The reportable healthstate information may be transmitted to one or more destinationsassociated with the customer (element 2234). In some embodiments, adecision as to whether an indication of an indeterminate health state(e.g., if the confidence level threshold is not reached) is to beprovided may be based at least in part on client-specifiedpreferences—e.g., a client may indicate via a programmatic interfacewhether only high-confidence results are to be provided or indeterminateresults are to be provided as well.

FIG. 23 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which enables clientsto request network health state information via programmatic interfaces,according to at least some embodiments. As shown in element 2301, adetermination may be made that a request for network health stateinformation pertaining to a client account has been received via aprogrammatic interface. Various types of programmatic interfaces may beused in different embodiments, including for example an API, a web-basedconsole, a command-line tool, or a graphical user interface. The requestmay include one or more parameters corresponding to respective elementsof health state request 502 of FIG. 5 in some embodiments such as anidentifier of the client account, targeted resources or services,endpoint pair categories of interest, and so on. In at least oneembodiment, filtering parameters included in the request may indicatethat instead of providing health state information for all endpoint paircategories associated with the client account, the response shouldprovide health state information for a subset, or that only some subsetsof aggregated metrics should be provided. In one embodiment, a healthstate information request may include respective custom definitions ofone or more health states—e.g., the client may indicate a rule to beused to designate an endpoint pair category as being in a partiallyimpaired state or an extensively impaired state. In various embodiments,at least some of the parameters of a health state request may beoptional, so that the service does not require all clients to provideall the elements indicated in FIG. 5. In some embodiments, the requestmay indicate that the client wishes to subscribe to updates regardinghealth state—e.g., that respective health state messages are to beprovided periodically or based on detections of threshold events to oneor more destinations.

If the client account is not explicitly indicated in the request, theaccount may be identified, e.g., based on authorization-related sessioninformation or headers associated with the use of the programmaticinterface (element 2304). The set of endpoint pair categories for whichhealth state information is to be provided in response to the requestmay be determined (element 2307) if not explicitly indicated in therequest, e.g., by communicating with control-plane components of one ormore other network-accessible services such as a virtualized computingservice. As mentioned above, the path between the endpoints of acategory may comprise a virtual representation of one or more physicalnetwork links in various embodiments.

Corresponding to each of the identified endpoint pair categories,respective sets of network metrics may be obtained from various datasources (which may in some cases include one or more physical networkdevices used for the traffic associated with a category) and/orintermediary tools in the depicted embodiment (element 2310). Theunderlying data sources may correspond to various levels of thehardware/software stacks, such as the kinds of entities shown in FIG. 6,and the corresponding metrics may be collected at various levels of aresource hierarchy similar to that shown in FIG. 7. In variousembodiments, respective weights or trust scores may be assigned to themetrics sets and/or intermediary tools as discussed above.

The metrics obtained from the various sources and tools may becorrelated and aggregated as discussed earlier (e.g., in the context ofFIG. 22) to generate respective health state descriptors for theendpoint pair categories (element 2313). In at least some embodiments, ahealth state descriptor may contain impairment-related summary stateinformation, as well as supporting aggregated statistics regardingvarious lower-level metrics such as an average packet drop rate, averageand percentiles for latencies, request/response success rates etc. Insome embodiments, a given health state descriptor may comprise elementssimilar to those shown in FIG. 4. Based on the contents of the generateddescriptors and/or on the filtering parameters or criteria indicated inthe health state request, a response may be generated (element 2316) andtransmitted via a programmatic interface to one or more destinations(element 2319). In some embodiments, upon receiving a response to aparticular health state request, a client may submit a follow-on requestfor additional information or evidence. In one such embodiment, thehealth state descriptor may contain more information than is provided inthe first response; for example, statistics regarding individual metricsor information regarding data sources/tools included in the descriptormay not be provided in the first response, but may be used for follow-onrequests.

FIG. 24 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which providescustomizable graphical representations of network health stateinformation, according to at least some embodiments. As shown in element2401, a determination may be made that a graphical representation ofnetwork health state information for resources associated with a clientaccount is to be prepared. In some cases, the determination may beresponsive to an explicit request (e.g., received via an API or via aweb-based management console implemented by a network-accessible serviceof the provide network). In other cases, if and when an entity or userassociated with the client account successfully logs in to a managementconsole implemented by a service of the provider network, the successfullogin may trigger the determination that the graphical representation isto be provided. One or more characteristics or constraints (e.g. size inpixels) of the client-side display device may be determined, e.g., basedon network headers or other metadata received from the client (element2404).

The set of resources associated with the client account, andcorresponding endpoint pair categories, may be identified (element2407), e.g., using information obtained from control-plane components ofone or more services as discussed earlier. As mentioned above, the pathbetween the endpoints of a category may comprise a virtualrepresentation of one or more physical network links in variousembodiments. Respective network metrics groups/sets corresponding tovarious data sources of the kind discussed above (which may in at leastsome cases include physical network devices used for traffic associatedwith an endpoint pair category) may be obtained (element 2410),including at least some metrics associated with non-public resources.

The metrics may be parsed and correlated using approaches similar tothose described earlier, to obtain respective health state descriptorsfor various endpoint pair categories relevant to the client account(element 2413). Based at least in part on the display characteristicsand/or the number of endpoint pair categories for which health stateinformation is available, the summarization level of network healthinformation may be determined (element 2416). For example, if the numberof distinct endpoint pair categories is such that showing metrics forall the categories separately may clutter the display, metricscorresponding to several different endpoint pair categories or resourcesmay be combined to produce summarized information for display. In oneembodiment, for example, metrics pertaining to traffic flow between thepublic Internet and several different isolated virtual networksconfigured on behalf of the customer may be aggregated to a single“IVN-to-Internet” summary metric. Such summarization/combination mayrequire rules for combining health state information—e.g., if any one ofN IVNs has a severely-impaired network health status with respect to thepublic Internet, the summarized information may also indicate severimpairment in one implementation, even if (N-1) of the IVNs are notimpacted by the impairment.

A data set usable to display a graphical representation of the resourcesassociated with the client account, as well as the network health statesdetermined for various relevant endpoint pair categories, may begenerated (element 2419). The data set may then be transmitted to one ormore client-side devices (element 2422) where the display is provided.Optionally, a client may indicate a refresh rate for the display, inwhich case updated data sets based on received metrics may betransmitted at intervals corresponding to the refresh rate.

FIG. 25 is a flow diagram illustrating aspects of operations that may beperformed at a network health management service which filters networkhealth information based on customer impact, according to at least someembodiments. As shown in element 2501, a network health impairment eventassociated with one or more resources of a provider network may bedetected, e.g., using network metrics collected from a variety of toolsand/or data sources. Tools similar to those discussed in the context ofFIG. 13-FIG. 19 may be used in some embodiments, and the raw metrics maybe obtained from data sources illustrated in FIG. 6 at various levels ofa resource hierarchy similar to that shown in FIG. 7. The healthimpairment event may, for example, correspond to a software or hardwarefailure at one or more devices of the provider network, such as avirtualization host, a physical network link, a router, gateway, switchor the like.

The network health management service may analyze the impact of theimpairment event on the applications of various customers (element2504). For example, a list of the provider network services being usedby a customer may be examined, location information pertaining to theimpaired/failed devices or modules may be correlated with locationinformation of client resources, metrics captured from packet tracingsessions at the encapsulation protocol processing layer of a virtualizedcomputing service or other services may be analyzed, and so on. In atleast some embodiments, aspects of the networking configuration settingspertaining to the impaired resources and/or customer resources may becompared—e.g., subnet information associated with a given virtualmachine, host or network device may enable the NHMS to ascertain whethera given customer would be affected by a failure. In one embodiment, aninventory management system of the provider network may contain locationinformation (e.g., at the rack level, room level, data center level,availability container level, or region level) for various resources,and the proximity of the hosts being used for a given customer'sapplications to the impaired device(s) may be determined to estimate aprobability of a negative impact of the impairment on the applications.

With respect to a customer C1, on whose behalf resources are allocatedwithin a particular data center DC1 of an availability container AC1 atwhich the impairment event occurred, the network health managementservice may determine that the probability of a negative impact on C1'sapplications is below a threshold (element 2513). As a consequence, thenetwork health management service may cause a health state message M1 tobe transmitted to a destination (e.g., a client device at which agraphical representation of the client's resources can be shown)associated with C1. M1 may indicate that the state of one or moreendpoint pair categories relevant to C1 (or specific resources allocatedto C1) is unimpaired (element 2522). In effect, despite the fact thatthe impairment event occurred in a data center where C1 was allocatedsome resources, the network health state information provided to C1 maybe filtered to avoid an indication that C1's applications are impacted.

In contrast, the network health management service may determine thatthe probability of a negative impact on customer C2's applications,which may also be using resources of DC1 and AC1, exceeds the threshold(element 2517). As a result, a different health state message M2 may betransmitted to a destination affiliated with C2, indicating that theimpairment event has occurred and/or indicating that one or moreendpoint pair categories relevant to C2 are in an impaired state(element 2526). Similar customer-specific health state messages may beprepared for numerous other customers as well; the discussion ofcustomers C1 and C2 is not intended to indicate that the filtering ofnetwork health state information is limited to any particular number ofcustomers. In some embodiments, the threshold probabilities used fordeciding whether or not an impairment event is to be reported to a givencustomer may be customizable—e.g., customers may indicate preferencesvia programmatic interfaces of the network health management service forthe conditions under which they should be informed regardingfailures/impairments. In at least one embodiment, an indication of theoccurrence of an impairment event may be provided to a customer even ifthe network health management service determines that the customer'sapplications are likely to be unaffected. This may be done, for example,to inform or reassure the customer affirmatively that while a failurehas been identified (and is being resolved/repaired), the customer's ownapplications are not going to be impacted.

It is noted that in various embodiments, at least some operations otherthan those illustrated in the flow diagram of FIG. 21-FIG. 25 may beused to implement the network health management techniques describedabove. Some of the operations shown may not be implemented in someembodiments or may be implemented in a different order, or in parallelrather than sequentially.

Use Cases

The techniques described above, of providing customizable and verifiednetwork health state information at various levels of granularity toclients of services implemented at provider networks may be useful in anumber of scenarios. To many customers, the resources of providernetwork services (such as a virtualized computing service or storageservice) may appear to be the equivalent of black boxes, with limitedvisibility provided into the devices used to implement the services.When a customer application running on provider network resourcesappears to misbehave or perform poorly, especially with respect tonetwork traffic, it may not be straightforward for the customer todetermine whether the apparent problem is a real problem, and if it is areal problem, whether the root cause lies with the application layer orin the infrastructure of the provider network. As such, techniques thatcollect metrics from multiple independent tools and aggregate themetrics to provide customer-specific health state information viaeasy-to-use interfaces may reduce the amount of effort wasted bycustomers in application-level debugging if a problem is caused byimpairments at the infrastructure level. Furthermore, by ensuring thatreports of network impairments are verified using multiple sources, andby filtering reports of network impairments based on the anticipated oractual impact on applications of specific customers to whom the reportsare being provided, false alarms regarding failures which would notaffect customers may be reduced.

Illustrative Computer System

In at least some embodiments, a server that implements a portion or allof one or more of the technologies described herein, including thetechniques to implement various components of a network healthmanagement service, tools and metrics collectors used by the networkhealth management service, other resources of provider networks involvedin network health state management, and the like may include ageneral-purpose computer system that includes or is configured to accessone or more computer-accessible media. FIG. 26 illustrates such ageneral-purpose computing device 9000. In the illustrated embodiment,computing device 9000 includes one or more processors 9010 coupled to asystem memory 9020 (which may comprise both non-volatile and volatilememory modules) via an input/output (I/O) interface 9030. Computingdevice 9000 further includes a network interface 9040 coupled to I/Ointerface 9030.

In various embodiments, computing device 9000 may be a uniprocessorsystem including one processor 9010, or a multiprocessor systemincluding several processors 9010 (e.g., two, four, eight, or anothersuitable number). Processors 9010 may be any suitable processors capableof executing instructions. For example, in various embodiments,processors 9010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 9010 may commonly,but not necessarily, implement the same ISA. In some implementations,graphics processing units (GPUs) may be used instead of, or in additionto, conventional processors.

System memory 9020 may be configured to store instructions and dataaccessible by processor(s) 9010. In at least some embodiments, thesystem memory 9020 may comprise both volatile and non-volatile portions;in other embodiments, only volatile memory may be used. In variousembodiments, the volatile portion of system memory 9020 may beimplemented using any suitable memory technology, such as static randomaccess memory (SRAM), synchronous dynamic RAM or any other type ofmemory. For the non-volatile portion of system memory (which maycomprise one or more NVDIMMs, for example), in some embodimentsflash-based memory devices, including NAND-flash devices, may be used.In at least some embodiments, the non-volatile portion of the systemmemory may include a power source, such as a supercapacitor or otherpower storage device (e.g., a battery). In various embodiments,memristor based resistive random access memory (ReRAM),three-dimensional NAND technologies, Ferroelectric RAM, magnetoresistiveRAM (MRAM), or any of various types of phase change memory (PCM) may beused at least for the non-volatile portion of system memory. In theillustrated embodiment, program instructions and data implementing oneor more desired functions, such as those methods, techniques, and datadescribed above, are shown stored within system memory 9020 as code 9025and data 9026.

In one embodiment, I/O interface 9030 may be configured to coordinateI/O traffic between processor 9010, system memory 9020, and anyperipheral devices in the device, including network interface 9040 orother peripheral interfaces such as various types of persistent and/orvolatile storage devices. In some embodiments, I/O interface 9030 mayperform any necessary protocol, timing or other data transformations toconvert data signals from one component (e.g., system memory 9020) intoa format suitable for use by another component (e.g., processor 9010).In some embodiments, I/O interface 9030 may include support for devicesattached through various types of peripheral buses, such as a variant ofthe Peripheral Component Interconnect (PCI) bus standard or theUniversal Serial Bus (USB) standard, for example. In some embodiments,the function of I/O interface 9030 may be split into two or moreseparate components, such as a north bridge and a south bridge, forexample. Also, in some embodiments some or all of the functionality ofI/O interface 9030, such as an interface to system memory 9020, may beincorporated directly into processor 9010.

Network interface 9040 may be configured to allow data to be exchangedbetween computing device 9000 and other devices 9060 attached to anetwork or networks 9050, such as other computer systems or devices asillustrated in FIG. 1 through FIG. 25, for example. In variousembodiments, network interface 9040 may support communication via anysuitable wired or wireless general data networks, such as types ofEthernet network, for example. Additionally, network interface 9040 maysupport communication via telecommunications/telephony networks such asanalog voice networks or digital fiber communications networks, viastorage area networks such as Fibre Channel SANs, or via any othersuitable type of network and/or protocol.

In some embodiments, system memory 9020 may be one embodiment of acomputer-accessible medium configured to store program instructions anddata as described above for FIG. 1 through FIG. 25 for implementingembodiments of the corresponding methods and apparatus. However, inother embodiments, program instructions and/or data may be received,sent or stored upon different types of computer-accessible media.Generally speaking, a computer-accessible medium may includenon-transitory storage media or memory media such as magnetic or opticalmedia, e.g., disk or DVD/CD coupled to computing device 9000 via I/Ointerface 9030. A non-transitory computer-accessible storage medium mayalso include any volatile or non-volatile media such as RAM (e.g. SDRAM,DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc., that may be included in someembodiments of computing device 9000 as system memory 9020 or anothertype of memory. Further, a computer-accessible medium may includetransmission media or signals such as electrical, electromagnetic, ordigital signals, conveyed via a communication medium such as a networkand/or a wireless link, such as may be implemented via network interface9040. Portions or all of multiple computing devices such as thatillustrated in FIG. 26 may be used to implement the describedfunctionality in various embodiments; for example, software componentsrunning on a variety of different devices and servers may collaborate toprovide the functionality. In some embodiments, portions of thedescribed functionality may be implemented using storage devices,network devices, or special-purpose computer systems, in addition to orinstead of being implemented using general-purpose computer systems. Theterm “computing device”, as used herein, refers to at least all thesetypes of devices, and is not limited to these types of devices.

Conclusion

Various embodiments may further include receiving, sending or storinginstructions and/or data implemented in accordance with the foregoingdescription upon a computer-accessible medium. Generally speaking, acomputer-accessible medium may include storage media or memory mediasuch as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile ornon-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.),ROM, etc., as well as transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The various methods as illustrated in the Figures and described hereinrepresent exemplary embodiments of methods. The methods may beimplemented in software, hardware, or a combination thereof. The orderof method may be changed, and various elements may be added, reordered,combined, omitted, modified, etc.

Various modifications and changes may be made as would be obvious to aperson skilled in the art having the benefit of this disclosure. It isintended to embrace all such modifications and changes and, accordingly,the above description to be regarded in an illustrative rather than arestrictive sense.

What is claimed is:
 1. A system, comprising: one or more computingdevices of a network health manager associated with a virtualizedcomputing service of a provider network; wherein the one or morecomputing devices are configured to: determine that a graphicalrepresentation of network health state information pertaining to aclient account of the provider network is to be prepared; identify afirst set of resources associated with the client account; generate,using one or more network metrics groups corresponding to respectivedata sources, a network health state descriptor corresponding to avirtual representation of one or more physical network links utilizedfor network traffic of at least a subset of resources of the first set,wherein at least a first metric of a particular network metrics group isobtained from a non-public networking device and is inaccessible to acustomer of the provide network, and wherein the network health statedescriptor comprises an impairment-related summary state; and transmit adata set usable to generate a graphical display of (a) a representationof the first set of resources and (b) network health state informationcorresponding to at least one resource of the first set of resources,wherein the data set is based at least in part on (a) the network healthstate descriptor and (b) one or more characteristics of a device to beused for the graphical display.
 2. The system as recited in claim 1,wherein the data set comprises respective network health stateinformation for a particular endpoint pair category comprising one of:(a) a first endpoint within one availability container of thevirtualized computing service and a second endpoint within a differentavailability container of the virtualized computing service, (b) a firstendpoint within one geographical region and a second endpoint within adifferent geographical region, (c) a first endpoint within a virtualizedcomputing service and a second endpoint at a customer data center, (d) afirst endpoint within a virtualized computing service and a secondendpoint within the public Internet, (e) a first endpoint within avirtualized computing service and a second endpoint within a differentnetwork-accessible service, or (f) a first endpoint within a firstisolated virtual network and a second endpoint outside the isolatedvirtual network.
 3. The system as recited in claim 1, wherein todetermine that a graphical representation of network health stateinformation pertaining to the client account is to be prepared, the oneor more computing devices are configured to: detect that a loginoperation to a management console of the virtualized computing servicehas succeeded, wherein the login operation was initiated by an entityassociated with the client account.
 4. The system as recited in claim 1,wherein the one or more network metrics groups comprise a plurality ofnetwork metrics groups, wherein the one or more computing devices areconfigured to: assign respective weights to individual ones of theplurality of network metrics groups; and utilize the respective weightsto generating the network health state descriptor.
 5. The system asrecited in claim 4, wherein a particular weight assigned to a particularnetwork metrics group is based at least in part on one or more of: (a) aphysical location of a resource to which the particular network metricsgroup corresponds, (b) a layer of a networking stack to which theparticular network metrics group corresponds, or (c) a collection timeof at least one metric of the particular network metrics group.
 6. Amethod, comprising: performing, by one or more computing devices:determining that a graphical representation of network health stateinformation pertaining to a client account of a provider network is tobe prepared; generating, using one or more network metrics groupscorresponding to respective data sources, a network health statedescriptor corresponding to a resource associated with the clientaccount, wherein at least a first metric of a particular network metricsgroup is obtained from a non-public networking device and isinaccessible to a customer of the provide network; and transmitting afirst data set usable to generate a graphical display of network healthstate information corresponding to at least one resource associated withthe client account, wherein the first data set is derived at least inpart from the network health state descriptor.
 7. The method as recitedin claim 6, further comprising performing, by the one or more computingdevices: combining, based at least in part on an indication of aproperty of a display device, metrics pertaining to a plurality ofresources associated with the client account; and including, within thefirst data set, a summarized metric resulting from said combining. 8.The method as recited in claim 6, further comprising performing, by theone or more computing devices: determining a targeted update rate of thegraphical display; and transmitting, in accordance with the targetedupdate rate, one or more updated data sets.
 9. The method as recited inclaim 6, further comprising performing, by the one or more computingdevices: determining that a zoom-in request to provide network healthstate information of individual resources of a group of resources hasbeen received; and transmitting a second data set usable to display thenetwork health state of individual resources of the group of resources.10. The method as recited in claim 6, wherein the first data set usableto generate the graphical display comprises an indication of a color tobe used to indicate a severity of a network health problem.
 11. Themethod as recited in claim 6, wherein the first data set comprisesrespective networking state information for a particular endpoint paircategory comprising one of: (a) a first endpoint within one availabilitycontainer of a virtualized computing service and a second endpointwithin a different availability container of the virtualized computingservice, (b) a first endpoint within one geographical region and asecond endpoint within a different geographical region, (c) a firstendpoint within a virtualized computing service and a second endpoint ata customer data center, (d) a first endpoint within a virtualizedcomputing service and a second endpoint within the public Internet, (e)a first endpoint within a virtualized computing service and a secondendpoint within a different network-accessible service, or (f) a firstendpoint within a first isolated virtual network and a second endpointoutside the isolated virtual network.
 12. The method as recited in claim6, wherein a first network metrics group of the one or more networkmetrics groups comprises a particular network metric obtained from oneor more of: (a) a user-mode process (b) a privileged process of anoperating system (c) a virtualization management component (d) a networkinterface card (e) a router (f) a switch or (g) an encapsulationprotocol processing device.
 13. The method as recited in claim 6,wherein the one or more network metrics groups comprise a plurality ofnetwork metrics groups, the method further comprising performing, by theone or more computing devices: assigning respective weights toindividual ones of the plurality of network metrics groups; whereingenerating a particular network health state descriptor comprisesutilizing the respective weights.
 14. The method as recited in claim 13,wherein a particular weight assigned to a particular network metricsgroup is based at least in part on one or more of: (a) a physicallocation of a resource to which the particular network metrics groupcorresponds, (b) a layer of a networking stack to which the particularnetwork metrics group corresponds, or (c) a collection time of at leastone metric of the particular network metrics group.
 15. The method asrecited in claim 6, further comprising performing, by the one or morecomputing devices: obtaining a particular network metric from one ormore of: (a) a tool configured to issue Domain Name Service (DNS)queries (b) a tool configured to run Virtual Private Network (VPN) testsor (c) a tool configured to run tests which utilize a dedicated physicallink established between the provider network and a customer networkingdevice.
 16. A non-transitory computer-accessible storage medium storingprogram instructions that when executed on one or more processors:determine that a graphical representation of network health stateinformation pertaining to a client account of a provider network is tobe prepared; generate, using one or more network metrics groupscorresponding to respective data sources, a network health statedescriptor corresponding to a resource associated with the clientaccount, wherein at least a first metric of a particular network metricsgroup is obtained from a non-public networking device of the providernetwork; and transmit a first data set usable to generate a graphicaldisplay of network health state information corresponding to at leastone resource associated with the client account, wherein the first dataset is derived at least in part from the network health statedescriptor.
 17. The non-transitory computer-accessible storage medium asrecited in claim 16, wherein the one or more network metrics groupscomprise a plurality of network metrics groups, wherein the instructionswhen executed on the one or more processors: assign respective weightsto individual ones of the plurality of network metrics groups; andutilize the respective weights to generate the network health statedescriptor.
 18. The non-transitory computer-accessible storage medium asrecited in claim 17, wherein a particular weight assigned to aparticular network metrics group is based at least in part on one ormore of: (a) a physical location of a resource to which the particularnetwork metrics group corresponds, (b) a layer of a networking stack towhich the particular network metrics group corresponds, or (c) acollection time of at least one metric of the particular network metricsgroup.
 19. The non-transitory computer-accessible storage medium asrecited in claim 16, wherein a particular metrics group of the one ormore metrics groups is generated at one of: (a) a tool configured toissue Domain Name Service (DNS) queries (b) a tool configured to runVirtual Private Network (VPN) tests or (c) a tool configured to runtests which utilize a dedicated physical link established between theprovider network and a customer networking device.
 20. Thenon-transitory computer-accessible storage medium as recited in claim16, wherein the first data set comprises respective network health stateinformation for a particular endpoint pair category comprising one of:(a) a first endpoint within one availability container of a virtualizedcomputing service and a second endpoint within a different availabilitycontainer of the virtualized computing service, (b) a first endpointwithin one geographical region and a second endpoint within a differentgeographical region, (c) a first endpoint within a virtualized computingservice and a second endpoint at a customer data center, (d) a firstendpoint within a virtualized computing service and a second endpointwithin the public Internet, (e) a first endpoint within a virtualizedcomputing service and a second endpoint within a differentnetwork-accessible service, or (f) a first endpoint within a firstisolated virtual network and a second endpoint outside the isolatedvirtual network.
 21. The non-transitory computer-accessible storagemedium as recited in claim 20, wherein the first data set comprises ahint pertaining to at least a portion of a layout of the graphicaldisplay, wherein the hint includes an indication of a logical orphysical relationship between a particular endpoint and anotherendpoint.
 22. The non-transitory computer-accessible storage medium asrecited in claim 20, wherein the first data set comprises arepresentation of a change in a health state of a particular resource,wherein the change in the health state is to be indicated via thegraphical display.
 23. The non-transitory computer-accessible storagemedium as recited in claim 20, wherein the first data set comprises arepresentation of a time series of network health data records of aparticular resource, wherein the time series is to be indicated via thegraphical display.